Patent Publication Number: US-11661915-B2

Title: Battery key, starter and improved crank

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 16/145,475, filed Sep. 28, 2018, which claims the benefit of U.S. Provisional Application No. 62/567,512 filed on Oct. 3, 2017. The entire disclosures of the above applications are incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to a vehicle engine and, more particularly, to a method and apparatus for starting an engine of a vehicle and associated engine features. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     A vehicle, such as a snowmobile, generally includes an engine assembly. The engine assembly is operated with the use of fuel to generate power to drive the vehicle. The power to drive a snowmobile is generally generated by a combustion engine that drives pistons and a connected crank shaft. Two-stroke snowmobile engines are highly tuned, high output, and high specific power output engines that operate under a wide variety of conditions. 
     Vehicles such as snowmobiles can be difficult to start in cold weather. This is true especially for two-stroke engines. Many snowmobiles are pull start. Pull starting a snowmobile can be difficult. There is much resistance to a pull as the pistons move over top dead center. 
     Adding vehicle components to start the vehicle add complexity and operability issues in extreme temperatures. Typically, starting systems require a battery. Due to the extreme cold temperatures snowmobiles face, the battery has to be sized very large to start the vehicle reliably. Oftentimes, recreational vehicles are used sporadically and maintaining a charge on a fixed vehicle battery is inconvenient. Further the weight of a battery and start can detract from the ride. Reduce weight is typically a goal to increase fuel economy. 
     SUMMARY 
     This section provides a general summary of the disclosures, and is not a comprehensive disclosure of its full scope or all of its features. 
     A. Engine and Starter Mounting Assembly and Method 
     According the present teachings, an engine is disclosed having a starter flywheel, and a crank case having an integral starter pinion accepting member defining a through bore, and a gear assembly having an exterior surface configured to engage the flywheel and a surface engaging the shaft. A starter pinion shaft is disposed through the through bore, and has a first end projecting from a first side of the integral starter pinion accepting member. The first end is configured to be coupled to a starter motor. The starter pinion shaft has a second end projecting from a second side of the integral starter pinion accepting member, and defines a drive surface supporting the gear assembly. The pinion shaft is supported by a bearing disposed between the shaft and the through bore integral surface. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the engine further has the second end of the pinion shaft defines a worm gear configured to bias the gear assembly in a first direction when the shaft is rotated. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the gear assembly has a gear defining an internally threaded bore and an externally threaded surface, the internally threaded bore being configured to engage the worm gear defined on the shaft. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the gear assembly has a return spring configured to bias the gear assembly exterior surface away from the flywheel when the shaft is not rotating. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the engine further has a locking flange annularly disposed about the shaft configured to couple the shaft to the starter pinion accepting member. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, wherein the shaft has a first end defining a flat configured to engage a flexible drive member. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, wherein the gear assembly has a dust cover disposed over a return spring. 
     According the present teachings, an engine is disclosed having engine crankcase having an integral starter pinion accepting member defining a through bore and an external bearing surface and a force transmitting member having an exterior fly wheel engaging surface and an interior surface configured a worm gear engaging surface. A shaft which is disposed through the through bore is provided. The shaft has worm gear coupled to the worm gear engaging surface. An engine mount coupled to the external bearing surface. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the gear assembly has a return spring configured to bias the gear assembly exterior surface away from the flywheel when the shaft is not rotating. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the engine further has further has a locking flange annularly disposed about the shaft configured to couple the shaft to starter pinion accepting member. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the gear assembly has a dust cover disposed over a return spring. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the engine mount has a cylindrical rubber bushing member and a support bracket having a raised lip which annularly surrounds a cylindrical rubber bushing member. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the engine further has the engine mount bracket has a threaded pin disposed through the rubber bushing which is used to couple the engine mount to the vehicle frame engaging member. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the rubber bushing member has an integrated plate member, the plate and bushing member each having a pair of projecting flanges which are aligned with a pair of flange accepting apertures defined in the vehicle frame engaging member. 
     According the present teachings, an engine mount is disclosed having a cylindrical rubber bushing member having a first pair of projecting flanges. The engine mount has an integrated plate member having a second pair of projecting flanges, the integrated plate member being at least partially disposed within the cylindrical rubber bushing member. A support bracket having a raised lip annularly surrounding the cylindrical rubber bushing member. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the engine mount bracket has a threaded pin disposed through the rubber bushing which is used to couple the engine mount to the vehicle frame engaging member. 
     According to an alternate teaching, the aforementioned paragraphs or the following paragraphs, the second pair of projecting flanges are at least partially disposed within the first pair of projecting flanges, wherein at least one of the first or second projecting flanges are aligned with a pair of flange accepting apertures defined in the vehicle frame. 
     B. Combustion Chamber and Exhaust Manifold Assembly and Method 
     According to the present teachings, a two-cycle engine for a vehicle is disclosed. The engine has a block defining an exhaust port and a cylinder, a head, and a piston defining a combustion chamber. The engine is configured to run at variable speeds that are determined by the rate fuel is being added to the combustion chamber. The exhaust port has a resonant frequency that, when not timed with the engine speed, causes a portion of the combusted and uncombusted exhaust gasses to flow from the exhaust system back into the combustion chamber. At a plurality of engine speeds below a predetermined engine speed, a majority of a portion of the combusted and uncombusted exhaust gasses flow from the exhaust system and impinge on the piston skirt before flowing back into the combustion chamber. At a speed above the predetermined speed, a majority of the portion of the combusted and uncombusted exhaust gasses flows from the exhaust system and back into the combustion chamber without engaging the skirt of the piston. 
     According to the aforementioned paragraph and the following paragraphs, the exhaust port includes an exhaust valve which selectively changes an aperture size of the exhaust port depending on the engine speed. 
     According to the aforementioned paragraphs and the following paragraphs, the exhaust port has a resonant frequency that depends on the position of the exhaust valve. 
     According to the aforementioned paragraphs and the following paragraphs, the exhaust port is an elongated passage fluidly coupled to the combustion chamber. The elongated fluid passage being angled and having a flow direction away from the engine head. 
     According to the aforementioned paragraphs and the following paragraphs, the head of the engine has a surface representing a portion of a cutaway of a horn torus that defines a portion of the combustion chamber. 
     According to the aforementioned paragraphs and the following paragraphs, the head of the engine has a surface representing a portion of a cutaway of a torus which defines a portion of the combustion chamber and the engine further has a sparkplug which positions a spark initiating member centrally within the torus. 
     According to the aforementioned paragraphs and the following paragraphs, the head of the engine has a surface representing a cutaway portion of a torus which defines a volume of greater than about 9% percent of the combustion chamber volume when the piston is at top dead center. 
     According to the present teachings, and the previous and following paragraphs, presented is an engine having an engine block, cylinder wall, piston having a skirt, and head defining a combustion chamber. Defined within the cylinder wall is an exhaust port having resonant frequency that causes a portion of combusted and uncombusted exhaust gasses to flow from the exhaust system and back into the combustion chamber. At a plurality of engine speeds a majority of a portion of the combusted and uncombusted exhaust gasses flows from the exhaust system and back into the combustion chamber after impinging on to the piston skirt. At a speed above the predetermined speed, a majority of the portion of the combusted and uncombusted exhaust gasses flows from the exhaust system and back into the combustion chamber without significantly engaging the skirt of the piston. 
     According to the present teachings, and the previous and following paragraphs, presented is an engine having an exhaust port defining an elongated channel, flow from said combustion chamber into the exhaust port flows at an angle obtuse to a centerline of the piston travel and away from the cylinder head. 
     C. Vehicle Cooling Assembly and Method 
     The present disclosure teaches an improved system and method for reliably managing two cycle engine heat, and particularly two cycle engine heat snowmobile. The system moves the cooling system bypass check valve out of the engine and into a location in a cooling system which is subjected to significantly lower vibrational energy. 
     According to the present teachings, presented is coolant reservoir configured to be placed within a vehicle cooling system. The coolant reservoir has a bottle that defines a first chamber and a second chamber fluidly coupled to the first chamber through an aperture having a valve seat. The first chamber is fluidly coupled to a source of heated engine cooling fluid, while the second chamber is fluidly coupled to an engine water pump. A thermally responsive actuator having a sliding member and a valve seat engaging surface is disposed within the first chamber. The sliding member is movable from a first open position to a second closed position when the coolant is above a first temperature. 
     According to the aforementioned paragraph and the following paragraphs, a first spring can be engaged between the sliding member and the coolant bottle and is operative to urge the sliding member in a first direction relative to the valve seat. A second spring can be engaged between the sliding member and the coolant bottle and operative to urge the valve seal in a second direction relative to the valve seat. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir can have a first member defining a first portion of the first chamber and a first portion of the second chamber. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir can have a second member defining a second portion of the first chamber, and wherein the thermally responsive actuator has a flange member couple to the second member. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir can have a first member defines a first portion of the first chamber and a first portion of the second chamber. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir can have a first member defining a first chamber first aperture fluidly coupled to the engine water pump. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir can have a first member defining a first chamber first aperture fluidly coupled to the source of heated engine cooling fluid. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir can have first member defining a bypass aperture between the first and second chambers having the valve seat, whereby the valve seat engaging surface is positioned adjacent the bypass aperture. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir can have the thermally responsive actuator axially coupled to the bottle. 
     According to the aforementioned paragraphs and the following paragraphs, the coolant reservoir first member defines a first chamber second aperture fluidly coupled to a cooling chamber. 
     According to the aforementioned paragraphs and the second member defines a first chamber second aperture fluidly coupled to the cooling chamber. 
     According to the present teachings, and the previously mentioned and following paragraphs, presented is coolant reservoir configured to be placed within a vehicle cooling system. A coolant bottle formed of at least first and second members. The first and second members define a first chamber, and the first member further forms a portion of a second chamber. The first and second chambers are fluidly coupled through an aperture having a valve seat. The first chamber is fluidly coupled to a source of heated engine cooling fluid, and the second chamber is fluidly coupled to an engine water pump. The bottle has a thermally responsive actuator disposed within the first chamber that has a sliding member having a valve seat engaging surface. The sliding member is movable from a first open position when the coolant is below a first temperature to a second position when the coolant is above the a first temperature. 
     According to the present teachings, and the previously mentioned and following paragraphs wherein the first member defines a second chamber first aperture fluidly coupled to the engine water pump. 
     According to the present teachings, and the previously mentioned and following paragraphs wherein the first member further defines a second chamber first aperture fluidly coupled to the source of heated engine cooling fluid. 
     According to the present teachings, and the previously mentioned and following paragraphs wherein the first member defines a second chamber second aperture fluidly coupled to a heat exchange chamber. 
     According to the present teachings, and the previously mentioned and following paragraphs wherein the second member defines a first chamber second aperture fluidly coupled to the heat exchange chamber. 
     According to the present teachings, and the previously mentioned and following paragraphs further comprising a third member defining a closable third coolant accepting aperture. 
     According to the present teachings, and the previously mentioned and following paragraphs further having a conical swirl plate member disposed between the third chamber and second chamber, the conical swirl plate member defines a plurality of coupling apertures fluidly coupling the second and third chambers. 
     According to the present teachings, and the previously mentioned and following paragraphs where the sliding valve element has a second exterior bearing surface which is configured to engage a first end of the second intermediate spring. 
     According to the present teachings, and the previously mentioned and following paragraphs wherein the sliding valve element bearing surface slidably supports the valve seal and regulates the movement of the valve seal toward and away from the valve seat. 
     According to the present teachings, and the previously mentioned and following paragraphs wherein the thermally responsive actuator includes a retractable piston, the thermally responsive actuator is configured to retract the piston and thereby position the sliding valve element in an open position. 
     According to the present teachings, and the previously mentioned and following paragraphs where the thermally responsive actuator includes a retractable piston, the thermally responsive actuator is configured to retract the piston and thereby position a valve seal stop on the sliding valve element in an open position. 
     According to the present teachings, and the previously mentioned and following paragraphs, presented is coolant reservoir configured to be placed within a vehicle cooling system. The coolant reservoir has a first member defining first and second chambers and a first bypass passage having a first valve seat there between. The first chamber is fluidly coupled to a heated engine fluid supply and the second chamber is fluidly coupled to an engine fluid return. The bottle includes a thermally responsive actuator that moves a valve bearing element between an open and closed positions. The thermally responsive actuator includes a sliding valve element disposed within the first chamber and a valve seal which is configured to engage the first valve seat. The sliding valve element has a second exterior bearing surface which is configured to fixably engage the first member. The thermally responsive actuator is operably engaged between the sliding valve element and the bottle and operative to urge the sliding valve element away the valve seat and wherein the second spring is engaged between the sliding valve element and the valve seal and operative to urge the valve seal toward the valve seat. 
     According to the present teachings, and the previously mentioned and following paragraphs where the first member defines a second chamber first aperture fluidly coupled to the engine water pump. 
     According to the present teachings, and the previously mentioned and following paragraphs where the first member further defines a second chamber first aperture fluidly coupled to the source of heated engine cooling fluid. 
     According to the present teachings, and the previously mentioned and following paragraphs where the first member defines a second chamber second aperture fluidly coupled to a heat exchange chamber. 
     According to the present teachings, and the previously mentioned and following paragraphs where the second member defines a first chamber second aperture fluidly coupled to the heat exchange chamber. 
     D. Stator Cooling Assembly and Method 
     An alternator that is powered by an engine may generally include at least two components including a stator unit and a moving rotor component. In various embodiments, the rotor component rotates by being driven by a crank shaft. For example, the crank shaft is connected to a fly wheel component that moves relative to a stator. In various embodiments, the fly wheel moving relative to the stator may be referred to as a generator or an alternator flywheel. 
     Because of movement of the rotor relative to the stator, a current is generated through coils or windings of the stator. In addition to the current, resistance to the current in the windings may generate thermal energy. Movement of the rotor, with or due to the fly wheel, may also generate thermal energy. An increase of temperature may occur due to the presence of the thermal energy. A fan assembly may, therefore, be associated with the rotating component, such as the fly wheel, to assist in removing or dissipating the thermal energy and reducing the lowering of temperature of the stator or alternator assembly. 
     E. Vehicle Starter System and Method 
     The present disclosure also provides an improved method for reliably starting a vehicle, particularly a snowmobile. 
     In one aspect of the disclosure, a system for starting an engine comprises a fuel injector that injects fuel into a closed intake port to form an air fuel mixture, an actuator rotating a crankshaft in a first direction to open the intake port by moving a piston within a cylinder coupled to the crankshaft and a combustion chamber defined between the cylinder and the port receiving the air fuel mixture through the intake port. The actuator rotates the crankshaft in a second direction to close the intake port and compress the fuel mixture. A spark plug ignites the air fuel mixture to start the engine. 
     In another aspect of the disclosure, a method of starting an engine of a vehicle comprises injecting fuel into a closed intake port to form an air fuel mixture, rotating a crankshaft in a first direction to open the intake port by moving a piston within a cylinder coupled to the crankshaft, receiving the air fuel mixture through the intake port in a combustion chamber defined between the cylinder and the port, rotating the crankshaft in a second direction to close the port and igniting the air fuel mixture to start the engine. 
     In yet another aspect of the disclosure, a method of starting an engine of a vehicle comprising coupling a battery key to a controller of the vehicle, said battery key comprising a key identifier, communicating a key identifier from the battery key to a controller of the vehicle, said controller having a stored identifier, comparing the stored identifier and the key identifier, and, in response to comparing, providing power from the battery key to an actuator to rotate a crankshaft of the engine. 
     In yet another aspect of the disclosure, a system for starting an engine of a vehicle comprises a controller disposed within the vehicle and a battery key coupled to the controller of the vehicle. The battery key communicates a key identifier to the controller of the vehicle. The controller has a stored identifier therein. The controller compares the stored identifier and the key identifier. The controller, in response to comparing, provides power from the battery key to an actuator to rotate a crankshaft of the engine. 
     F. Fuel Management System and Method 
     The present disclosure also provides an improved method for operating an engine, particularly a two-stroke engine for a snowmobile. 
     In one aspect of the disclosure, a system of operating the same includes a fuel injector, a fuel pressure sensor generating a fuel pressure signal, and a controller coupled to the fuel pressure sensor and the fuel injector. The controller prevents a fuel injector from injecting fuel into the engine when the fuel pressure is below a fuel pressure threshold. The controller injects fuel into the engine when the fuel pressure is above the fuel pressure threshold. 
     In another aspect of the disclosure, a method of initiating starting of a two-stroke engine, determining fuel pressure, when the fuel pressure is below a fuel pressure threshold, preventing a fuel injector from injecting fuel into the engine, and when the fuel pressure is above the fuel pressure threshold, injecting fuel into the engine. 
     In yet another aspect of the disclosure, a method operating an engine includes determining a first pulse width duration for a fuel injector based on engine speed and throttle position, determining a barometric pressure, when the first pulse width duration is less than a minimum duration, determining a second pulse width duration as a function of barometric pressure, and operating the fuel injector with the second pulse width duration. 
     In yet another aspect of the disclosure, a system for operating an engine includes a fuel injector, an engine speed sensor, a barometric pressure sensor generating a barometric pressure signal corresponding to a barometric sensor and a controller coupled to the fuel injector, engine speed sensor, the barometric pressure sensor and the fuel injector. The controller determines a first pulse width duration for operating the fuel injector based on engine speed and throttle position, said controller determining a second pulse width duration as a function of barometric pressure when the first pulse width duration is less than a minimum duration, and communicating a pulse having a second pulse width duration. The fuel injector operates with the second pulse width duration. 
     In yet another aspect of the disclosure, a method of operating an engine comprises determining a first pulse width duration for a fuel injector based on engine speed and throttle position, determining at least one of a fuel pressure and a fuel temperature, and determining a pulse width correction factor as a function of at least one of a fuel pressure and a fuel temperature. The method further comprises determining a second pulse duration based on the pulse width correction factor and operating the fuel injector with the second pulse width duration. 
     In yet another aspect of the disclosure, a system of operating an engine comprises a fuel injector, an engine speed sensor generating an engine speed signal corresponding to an engine speed, a throttle position sensor generating a throttle position signal corresponding to a throttle position, a sensor module comprising at least one of a fuel pressure sensor generating a fuel pressure signal corresponding to a fuel pressure into the engine and a fuel temperature sensor generating a fuel pressure signal corresponding to a fuel pressure into the engine. A controller is coupled to the fuel injector, the engine speed sensor and the sensor module. The controller determines a pulse width duration for the fuel injector based on engine speed and throttle position, determining a pulse width correction factor as a function of at least one of the fuel temperature signal and the fuel pressure signal, determining a second pulse width duration based on the first pulse width, and operating the fuel injector with the second pulse width duration. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG.  1    is a perspective view of a snowmobile. 
         FIG.  2    is an exploded view of the snowmobile of  FIG.  1   . 
         FIGS.  2 A and  2 B  are enlarged exploded views of  FIG.  2   . 
         FIGS.  3 A and  3 B  are opposite side views of the engine of  FIG.  2   . 
         FIG.  4    is an exploded view of the engine of  FIG.  3   . 
         FIGS.  5 A- 5 C  are views of an engine components of an integral starter pinion and engine mount. 
         FIGS.  6 A and  6 B  represent sectional and exploded views of the integral starter pinion and engine mount shown in  FIG.  5 A . 
         FIGS.  7 A and  7 B  represent sectional and perspective views of the engine mount according to the present teachings. 
         FIGS.  8 - 13    represent cross sectional views of the engine shown in figure at various times of the engine rotation; 
         FIG.  14    represents a cross section of the head shown in  FIGS.  8 - 13   ; and 
         FIG.  15    represents a perspective view of the head shown in  FIGS.  8 - 14   . 
         FIG.  16    is a block diagrammatic view of a cooling system for a vehicle. 
         FIG.  17    is a view of a coolant reservoir bottle configured to be placed within a vehicle cooling system in  FIG.  16   . 
         FIGS.  18 A and  18 B  are cross sectional views of a coolant reservoir configured to be placed within the vehicle cooling system shown in  FIG.  16    with a valve elements in opened and closed positions respectfully. 
         FIGS.  19 A and  19 B  are perspective views of a thermally activated valve according to the present teachings. 
         FIG.  20    is a perspective view of an engine having improved cooling fluid flow according to the present teachings. 
         FIGS.  21 A and  21 B  represent front and rear views of the flow of cooling fluid through an engine according to the present teachings. 
         FIG.  21 C  is a sectional view of the cooling lines around the exhaust valves. 
         FIG.  22    is a side cross sectional view of the engine show in  FIG.  20   . 
         FIG.  23    is a detail exploded view of a generator portion of the engine assembly; 
         FIG.  24    is a perspective view of a fan assembly; 
         FIG.  25    is a cross-section view of the fan assembly along lines  7 - 7 ; and 
         FIG.  26    is a detail view of a portion of the fan assembly of  FIG.  24   . 
         FIG.  27    is a block diagrammatic view of a handheld/removable battery key module in relation to the vehicle. 
         FIG.  28    is a block diagrammatic view of the vehicle controller illustrated in  FIG.  27   . 
         FIG.  29    is a perspective view of a handheld/removable battery key module; 
         FIG.  30    is a block diagrammatic view of the handheld/removable battery key module; 
         FIG.  31    is a schematic of the electrical circuit for the battery key module; 
         FIG.  32    is a flow chart of a method for starting a vehicle using the handheld/removable battery key module; 
         FIG.  33    is a perspective view of a flywheel according to the present disclosure; 
         FIG.  34    is a linear view of the outside of the flywheel relative to the first track, second track and teeth all relative to the degree of rotation of the flywheel; 
         FIG.  35    is a flow chart for determining the direction of the tracks; 
         FIG.  36    is a flow chart of a method for starting a vehicle with a handheld battery without crossing top dead center; 
         FIGS.  37 A- 37 C  are various stages of the engine during starting. 
         FIG.  38    is a block diagrammatic view of the engine controller relative to a plurality of sensors in the engine. 
         FIG.  39 A  is table of first pulse timing for fuel pressure versus water temperature of the engine. 
         FIG.  39 B  is a plot of injector flow characteristics. 
         FIG.  39 C  is a plot of the correction authority determined in response to barometric pressure. 
         FIG.  40 A  is a schematic view of the temperature and pressure sensor. 
         FIG.  40 B  is a side view of the temperature and pressure sensor shown with adjacent fuel line input and output. 
         FIG.  41    is a flowchart of a method for correcting a minimum pulse width duration using barometric pressure. 
         FIG.  42    is a flowchart of a method for starting the engine using a first pulse and then correcting for fuel pressure and fuel temperature. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. Although the following description includes several examples of a snowmobile application, it is understood that the features herein may be applied to any appropriate vehicle, such as motorcycles, all-terrain vehicles, utility vehicles, moped, scooters, etc. The examples disclosed below are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed in the following detailed description. Rather, the examples are chosen and described so that others skilled in the art may utilize their teachings. 
     Referring now to  FIGS.  1  and  2   , one embodiment of an exemplary snowmobile  10  is shown. Snowmobile  10  includes a chassis  12 , an endless belt assembly  14 , and a pair of front skis  20 . Snowmobile  10  also includes a front-end  16  and a rear-end  18 . 
     The snowmobile  10  also includes a seat assembly  22  that is coupled to the chassis assembly  12 . A front suspension assembly  24  is also coupled to the chassis assembly  12 . The front suspension assembly  24  may include handlebars  26  for steering, shock absorbers  28  and the skis  20 . A rear suspension assembly  30  is also coupled to the chassis assembly  12 . The rear suspension assembly  30  may be used to support the endless belt  14  for propelling the vehicle. An electrical console assembly  34  is also coupled to the chassis assembly  12 . The electrical console assembly  34  may include various components for displaying engine conditions (i.e., gauges) and for electrically controlling the snowmobile  10 . 
     The snowmobile  10  also includes an engine assembly  40 . The engine assembly  40  is coupled to an intake assembly  42  and an exhaust assembly  44 . The intake assembly  42  is used for providing fuel and air into the engine assembly  40  for the combustion process. Exhaust gas leaves the engine assembly  40  through the exhaust assembly  44 . An oil tank assembly  46  is used for providing oil to the engine for lubrication and for mixing with the fuel in the intake assembly  42 . A drivetrain assembly  48  is used for converting the rotating crankshaft assembly from the engine assembly  40  into a potential force to use the endless belt  14  and thus the snowmobile  10 . The engine assembly  40  is also coupled to a cooling assembly  50 . 
     The chassis assembly  12  may also include a bumper assembly  60 , a hood assembly  62  and a nose pan assembly  64 . The hood assembly  62  is movable to allow access to the engine assembly  40  and its associated components. 
     Referring now to  FIGS.  3 A,  3 B and  4   , the engine assembly  40  is illustrated in further detail. The engine assembly  40  is a two-stroke engine that includes the exhaust assembly  44  that includes an exhaust manifold  45  and an exhaust pipe  47 . 
     The engine assembly  40  may include spark plugs  70  which are coupled to a one-piece cylinder head cover  72 . The cylinder head cover  72  is coupled to the cylinder head  74  with six bolts which is used for housing the single-ring pistons  76  to form a combustion chamber  78  therein. The cylinder head  74  is mounted to the engine block  80 . 
     The fuel system  82  that forms part of the intake assembly  42 , includes fuel lines  84  and fuel injectors  86 . The fuel lines  84  provide fuel to the fuel injectors  86  which inject fuel, in this case, into a port adjacent to the pistons  76 . An intake manifold  88  is coupled to the engine block  80 . The intake manifold  88  is in fluidic communication with the throttle body  90 . Air for the combustion processes is admitted into the engine through the throttle body  90  which may be controlled directly through the use of an accelerator pedal or hand operated switch. A throttle position sensor  92  is coupled to the throttle to provide a throttle position signal corresponding to the position of a throttle valve of throttle plate  94  to an engine controller discussed further herein. 
     The engine block  80  is coupled to crankcase  100  and forms a cavity for housing the crankshaft  102 . The crankshaft  102  has connecting rods  104  which are ultimately coupled to the pistons  76 . The movement of the pistons  76  within the engine chamber  78  causes a rotational movement at the crankshaft  102  by way of the connecting rods  104 . The crankcase may have openings or vents  106  therethrough. 
     The system is lubricated using oil lines  108  which are coupled to the oil injectors  110  and an oil pump  112 . 
     The crankshaft  102  is coupled to a generator flywheel  118  and having a stator  120  therein. The flywheel  118  has crankshaft position sensors  122  that aid in determining the positioning of the crankshaft  102 . The crankshaft position sensors  122  are aligned with the teeth  124  and are used when starting the engine, as well as being used to time the operation of the injection of fuel during the combustion process. A stator cover  126  covers the stator  120  and flywheel  118 . 
     Discussed below are various features of the engine assembly  40  used in the snowmobile  10 . Each of the features relate to the noted section headings set forth below. It should be noted that each of these features can be employed either individually or in any combination with the engine assembly  40 . Moreover, the features discussed below will utilize the reference numerals identified above, when appropriate, or other corresponding reference numerals as needed. Again, as noted above, while the engine assembly  40  is a two-stroke engine that can be used with the snowmobile  10 , the engine assembly  40  can be used with any appropriate vehicles and the features discussed below may be applied to four-stroke engine assemblies as well. 
     A. Engine and Starter Mounting Assembly and Method 
     As best seen in  FIGS.  5 A- 5 C , the engine assembly  40  has a starter pinion assembly  500  having an integrated engine mount  600 . The starter pinion assembly  500  has a pinion shaft  502  having a displaceable gear assembly  504  which engages an engine starter fly wheel  503 . The starter pinion assembly  500 , has an integrated monolithic starter pinion support member  506  that is cast and machined into the crankshaft case body. 
       FIGS.  5 B and  5 C  represent sectional and exploded views of the pinion assembly  502 . The starter pinion assembly  500  is integral formed into the crankcase at the integrated starter pinion support member  506 . The integral starter pinion accepting member  506  defines a through bore  508  which annually supports the shaft  502  using a pair of bearings  510 . The integral starter pinion accepting member  506  has first and second ends defining first and second apertures  507  and  509 , with first aperture  507  having a larger diameter than the second aperture  509 . The shaft  502  and displaceable gear assembly  504  are held to the integral starter pinion member  506  by a bracket  512  which defines a through aperture annularly disposed about the shaft  502 . The shaft  502  has a first end  514  which projects from a first end of the integral starter pinion accepting member  506  and through the aperture  508 . The first end  514  has an engaging surface which allows the coupling of the shaft  502  to a flexible starter cable (not shown). 
     The shaft  502  further has a medial portion  516  which is annularly supported by the bearings  510 . The bracket  512  defines a through bore  520  which is annularly disposed about the shaft  502 , and functions to hold the bearings  510  within the through aperture  508 . 
     Outside of the through aperture  508  is the displaceable gear assembly  504 . The displaceable gear assembly  504  has a shaft engaging member  530  which has an interior thread  532  that engages a worm thread  534  defined on an exterior surface  536  on the shaft  502 . The shaft engaging member  530  has a surface  538  which apply axial force onto a surface  540  of a gear  542  which during engagement of the starter axially displaces the gear  542  along a longitudinal axis of the shaft into engagement with the starter fly wheel  503 . 
     After the starter is disengaged, power to the displaceable gear assembly  504  is removed, stopping rotation of the shaft  502 . Return spring  544  applies return axial forces to the gear  542 , disengaging the gear  542  from the fly wheel  503 . Associated with the return spring is a pair of bearings  510  and a dust cover  548 . 
     As best seen in  FIGS.  6 A- 6 B , immediately adjacent the starter pinion assembly  500  and coupled thereto is the engine mount  600 . The engine mount  600  is coupled to the integral starter pinion accepting member  506  with a pair of fasteners  602 . 
     In this regard, the engine mount  600  has a bracket  604  having a raised lip  606  which annularly surrounds a cylindrical rubber bushing member  608 . Disposed through the bracket  604  and cylindrical rubber bushing member  608  is a threaded pin  610  which is used to couple the engine mount  600  to a vehicle from engaging member  612 . 
     As best seen in  FIGS.  7 A and  7 B , the rubber bushing member  608  has an integrated plate member  614 . The integrated plate member  614  and bushing member  608  have a pair of projecting ears or flanges  612  disposed at the bushing periphery  616  and off of a bushing top surface  618  which are aligned with a pair of square flange accepting apertures  614  defined in the vehicle frame engaging member  612 . The pair of projecting ears or flanges  612  disposed at the bushing periphery  616  and off of a bushing top surface  618  project along a line parallel to and displaced from an axis formed by the support pin. The pair of projecting ears or flanges  612  function as additional cushion and support along the force vectors most likely to induce damage to the bushing material. These apertures  612  and flanges align with the highest vibration loading vectors in the vehicle, thus increasing the expected life of the rubber bushing member  608 . In this regard, the pair of projecting flanges are positioned on a first surface of the rubber member and are radially displaced about a rubber bushing periphery at between 10 and 180 degrees to accept loading. 
     B. Combustion Chamber and Exhaust Manifold Assembly and Method 
       FIGS.  8 - 13    represent cross sectional views of the engine assembly  40  which are shown at various times of an engine piston rotation. The engine assembly  40  has a block  300 , such as block  80  defining an exhaust port  310  and a cylinder  312  defining the combustion chamber  324 , the engine head  74 , and the piston  76 . The engine assembly  40  is configured to run at variable speeds which changes as a fuel/air mixture is being added to the combustion chamber  324 . The exhaust port  310  has a resonant frequency that causes a portion of the combusted and uncombusted exhaust gasses to flow from the exhaust assembly  44  back into the combustion chamber  324 . At a plurality of engine speeds below a predetermined engine speed (about 6500), a majority of a portion and preferably more that 30% of the combusted and uncombusted exhaust gasses flow from the exhaust port  310  impinges on the piston skirt  315  prior to returning to the combustion chamber  324  with the remainder greater than 70% flowing past the skirt into the combustion chamber. 
     Preferably, at max torque and power output RPM of the engine, more than 70% of the returned exhaust gas from the exhaust port will bypass the piston skirt. At a speed above the predetermined speed (RPM?), a majority of the portion of the combusted and uncombusted exhaust gasses flowing from the exhaust port  310  and back into the combustion chamber  324  occurs without substantially engaging the skirt  315  of the piston  76 . The exhaust port  310  includes an exhaust valve  320  which moves within the exhaust port  310  to change the cross sectional area and shape of an aperture  322  in response to changing engine conditions such as engine speed. 
     The exhaust port  310  is an elongated passage  325  fluidly coupled to the combustion chamber  324  and to the exhaust assembly  44 . The elongated passage  325  is angled down at an obtuse angle with respect to the piston centerline, and is configured to direct hot exhaust gasses in a direction away from the engine head  74 . 
       FIG.  8 - 13    represent the movement of the piston  76  from its top dead center position in  FIG.  8    to a compression position in  FIG.  10   . As is normal in a two stroke engine, at top dead center, compressed fuel air mixture is initiated with a spark, thus driving the piston  76  down. In  FIGS.  6  and  7   , the piston reaches a point when the piston  67  engages and then passes the exhaust port  310  allowing compressed exhaust gasses to flow through the port  310 . In  FIG.  7   , the piston  76  reaches a fuel/air intake  77  which supplies the fuel/air mixture to the engine for the next engine stroke. The continued movement of the piston down in  FIG.  8    draws air and fuel from the fuel/air intake  77  as well as previously expelled exhaust gas and unburned fuel from the exhaust port  310 . 
     In  FIGS.  6  and  7   , the piston begins to move up toward top dead center placing the piston skirt  315  adjacent to the exhaust port  310 . Because the exhaust port  310  has a resonant frequency, a compressed wave of exhaust gas and unburned fuel travels in a direction toward the combustion chamber. At certain engine speeds, this compressed wave of exhaust gas hits the piston skirt  315  before the wave enters the combustion chamber. In this regard, below an engine RPM of about 6500 more than 30% of this compressed wave of exhaust gas hits the skirt  315  before entering the combustion chamber. Above this engine speed, more than 50% and preferably more than 70% of compressed wave of exhaust gas passes into the combustion chamber  324  without impinging on the piston skirt  315 . 
     The exhaust port  310  defines an elongated passage at an angle obtuse between 45 and 60 degrees to a centerline of the piston travel that directs flow of exhaust gasses away from the cylinder head  74 . The transfer port  79  fluidly coupled to the fuel/air cylinder intake  77 , said transfer port  79  having a fuel injector configured to provide fuel into the transfer port  79 . The exhaust port  310  has an exhaust port valve  320  which is actuatable to change an exhaust port aperture size. 
       FIG.  14    represents a cross section of the head  74  shown in  FIGS.  5 - 10   .  FIG.  12    represents a perspective view of the head shown in  FIGS.  8 - 14   . The engine head  74  has a concave interior surface  326  representing a portion of a cutaway of a horn torus. This surface  326  defines a portion of the combustion chamber  324 . The engine Assembly  40  has a sparkplug  70  centrally located in the horn torus which positions a spark initiating member  340  at a position between 35 and 40% of the from the piston  76  to the crown of the head surface. 
     The concave interior surface  326  (horn torus surface) has squish band surface area  330  which represents less than about 50% of the cylinder bore and preferably 48% of bore area. A major radius of curvature which leads to a second portion  327  having a radius of curvature that together define a portion of the combustion chamber  324 . Defined on the concave interior surface  326  is a projected member  329  that is annularly disposed about the spark plug  70 . The spark plug  70  is positioned 7.5 mm above piston dome, which can be about 35-45% and preferably 45% of combustion dome height, which represents about 10% of engine stroke. 
     The surface area of the concave portion represents about 705 of the bore area and 146% of the bore surface area. In this regard, the volume of the concave interior surface  326 . The concave region represents about 9.1% of cylinder displacement and the system has a Compression ratio 6.45:1. The smooth contours of the surface  326  allow for improved air fuel mixture within the piston draw down. In this regard, the smooth corners reduce null zones within the fuel/air mixture flow, thus improving combustion chamber efficiency. 
     C. Vehicle Cooling Assembly and Method 
       FIG.  16    is a block diagrammatic view of a cooling system for a vehicle. As described further below, the engine assembly  40  is water cooled, having a water pump  49  configured to push coolant fluid into the engine block  80  and through the engine assembly  40 . The heated coolant fluid leaves a source of heated engine cooling fluid  211  in the engine assembly  40 , which in this case originates from the cylinder head  74  of the engine assembly  40 , and travels to a coolant reservoir  200 . The coolant reservoir  200  has a bottle  202  configured to be placed within the vehicle cooling system. The bottle  202  defines first and second chambers  204  and  206  which are fluidly coupled together through an aperture  207 . Defined about the aperture  207  is a valve seat  208 . The first chamber  204  is fluidly coupled to the source of heated engine cooling fluid  211 , while the second chamber  206  is fluidly coupled to the engine water pump  49  which returns the coolant fluid back to the engine assembly  40 . 
     Upon exposure to heated fluid from the source of heated engine cooling fluid  211 , a thermally responsive actuator  212  closes the aperture  207  between the first and second chambers  204  and  206 , inducing the heated fluid from the engine assembly  40  to pass from the first chamber  204 , through a first chamber exit port  222  to a heat exchange chamber  262 . The heat exchanger  262  is configured to be cooled by moving snow that removes heat from the cooling fluid. This heat reduced cooling fluid is then returned to the second chamber  206  through an inlet port  226  where bubbles are allowed to escape into the third chamber  205 . The fluid is then transferred from the second chamber  206  through a second chamber exit port  228  to a hose  230  coupled to the water pump  49 . 
       FIG.  17    is an exterior view of the bottle  202  within the vehicle cooling system shown in  FIG.  5    with an interior valve element (not shown). The bottle  202  is formed of first, second, and third exterior members ( 232 ,  234 ,  236 ) which define the first, second and third chambers  204 ,  206 ,  205 . The first and second members  232  and  234  define the first chamber  204 , and the first member  232  further forms a portion of a second chamber  206 . The third chamber  205  which is fluidly coupled to the second chamber  234  is formed of the third funnel shaped exterior member  236 , which has a closable filling port  242  that allows the filling of the cooling system with coolant as needed. The first chamber  204  is fluidly coupled to the source of heated engine cooling fluid  211 , and the second chamber is fluidly coupled to the engine water pump  49  as described above. 
     As shown in  FIGS.  18 A and  18 B , the bottle  202  has a thermally responsive actuator  212  disposed within the first chamber  204 , and configured to move a thermally actuated sliding valve element  210  having the valve seat engaging surface or seal  208 . The thermally actuated sliding member  210  is movable from a first open position where the valve seal  209  engages the valve seat  208  that is displaced from the valve seat  208  to a second position when the coolant is below a first temperature. 
     As shown in  FIG.  18 A , when functioning, such as during vehicle startup, the thermally responsive actuator  212  is in an open position within the first chamber  204 . Fluid from the heated engine fluid supply  211  flows in to the first chamber  204 , past the thermally responsive actuator  212 , and valve seat  208  through the aperture  207  and into the second chamber  206 . The fluid then is returned directly to the water pump  49 . The sliding valve element  210  has a second exterior bearing flange  252  which is configured to engage the first member  232  to fixably couple the element to the bottle  202 . At temperatures below a first predetermined temperature cooling fluid is allowed to circulate directly into the engine at startup. 
       FIG.  18 B  is a cross sectional view of the bottle  202  with the thermally responsive actuator  212  in a closed position. When subjected to heated engine fluid, the thermally responsive actuator  212  thermal element  256  expands and thus translates the sliding valve element  210  and associated seal member  209  into engagement with the valve seat  208 . This closes the aperture  207  between the first and second chambers  204  and  206  which directs the heated fluid through the heat exchange chamber  262 . 
     The bottle  202  first member  232  defines the first chamber first aperture  258  fluidly coupled to a source of heated engine cooling fluid  211  (in this case the cylinder head  74 ). The second member  234  defines a first chamber second aperture  260  fluidly coupled to a cooling chamber  262 . The coolant reservoir first member  232  defines the second chamber second aperture  256  fluidly coupled to the cooling chamber  262  configured to receive cooled fluid from the cooling chamber  262 . 
     Disposed between the second and third chambers  206  and  205  is a conical swirl plate member  264 . The conical swirl plate member  264  defines a plurality of coupling apertures  266  fluidly coupling the second and third chambers  206  and  205 . These apertures  266  are configured to allow trapped gasses within the cooling system to escape from the second chamber  206  into the third chamber  205  as well as to allow coolant poured into the third chamber  205  through the closable filling port  242  to flow down into the second and third chambers  204  and  206  where it is incorporated into the cooling system. 
       FIGS.  19 A and  19 B  is a perspective view of the thermally responsive actuator  212  according to the present teachings. The thermally responsive actuator  212  is configured to retract the piston  270  and thereby position the valve seal member  209  away from the valve seat  208  when the thermally responsive actuator  212  is exposed to fluid temperatures below a predetermined value, in an open position (see  FIG.  7 A  above). The first and second springs  214  and  216  function to pull the thermally responsive actuator  212  way from the valve seat  208 , when the piston  270  is retracted. Similarly, the thermally responsive actuator  212  is configured to expel the piston  270  and thereby position the valve seal member  209  on the valve seat  208  when the thermally responsive actuator  212  is exposed to fluid temperatures above a predetermined value, in a closed position (see  FIG.  7 B  above). The sliding valve element  210  bearing surface slidably supports the valve seal member  209  and regulates the movement of the valve seal member  209  toward and away from the valve seat  208 . 
       FIG.  20    is a perspective view of an engine  40  having improved cooling fluid flow according to the present teachings.  FIGS.  21 A,  21 B and  21 C  represent front, rear and cross-sectional views of the flow of cooling fluid through the engine shown in  FIG.  20   .  FIG.  22    is a cross sectional view of engine showing the cooling apertures within the engine show in  FIG.  20   . With reference to these figures, the engine assembly  40  having the engine block  80  and cylinder head  74  define interior cooling chambers  250  which accept flowing cooling fluid. The velocity of the fluid at the entrance into the engine is greater than 2.1 m/s and preferably between 2.1 and 3.0 m/s. Fluid velocities for a second series of passages  254  annularly disposed about the exhaust port  256  are most preferably greater than 2.4 m/s and preferable remain between 2.1 and 3 m/s. Temperatures for the cooled regions can be between 275 degrees F. and 350 degrees F. 
     As shown, cooling fluid from the bottle  202  passes through the water pump  49  and into a first portion of the engine block at  252 . As this high velocity cooled fluid enters the engine block  80 , a first portion of the flow passes directly into the second series of passages  254  annularly disposed about the exhaust port  256  which is coupled to the exhaust assembly  44 . After cooling the engine components adjacent to the exhaust portion  256  this portion of the fluid flows into the cylinder head  74 . A second portion  258  of the flow passes directly into a third series of passages  260  annularly disposed about the cylinders and pistons  76 . After cooling the engine components adjacent to the cylinders this portion of the fluid flows into the cylinder head  74  and combines with the first portion of the fluid flow. This heated combined fluid flow exits the cylinder head  74 , and becomes the source of heated engine cooling fluid  211 . 
     D. Stator Cooling Assembly and Method 
     As discussed above in relation to  FIG.  4   , the engine assembly  40  includes various components, some of which move due to operation of the engine assembly  40 . The crank shaft  102  is connected to the fly wheel  118 . The fly wheel  118  includes various components, as discussed above, including the sensor interactors or teeth  124 . As also discussed above, the engine assembly  40  may include components that interact with the fly wheel  118  including the sensors  122  that may sense or interact with the teeth  124 . In addition, the fly wheel  118  includes a center or central connection region  1202 . The connection region  1202  may connect with or be connected to a terminal end  1204  of the drive shaft  102 . In various embodiments, a bolt or nut  1206  is connected to the terminal end  1204  of the crank shaft  102 . 
     Given the connection of the fly wheel  118  to the crank shaft  102 , upon rotation of the crank shaft  102 , the fly wheel  118  also rotates. The fly wheel  118  rotates relative to the stator  120 . The stator  120  is fixed relative to the crank case  100 . In particular, the crank case  100  includes an end housing  1208  that is coupled with the external cover  126 , the cover  126  may also be referred to as a stator or recoil cover. Covered by the cover  126  may be a generally known pull cord recoil system for starting the engine assembly  40 . The stator  120  is fixed relative to the crank case  100  in the housing  1208  and is fixed relative to the fly wheel  118 . Therefore, as the fly wheel  118  rotates relative to the stator  120 , an alternating current, of various phases and/or selected phases, is generated. The generated current may be carried away from the stator  120  according to various embodiments, such as via a wiring or wiring harness assembly (not illustrated). The fly wheel  118  may also have connected therewith a magnet ring  1212  that, therefore, also rotates relative to the stator  120 . 
     The operation of the engine assembly  40  may drive the crank shaft  102 . Operation or movement of the fly wheel  118  relative to the stator  120  may generate a current as noted above. Further, the generation of the current from the stator  120  may also generate thermal energy. The thermal energy may be due to resistance of one or more wires, such as those in a winding  1216 . The winding  1216  may include a plurality of windings  1216  formed on a core  1218  of the stator  120 . The core  1218  may include one or more projections or fingers  1220  on which the windings  1216  are placed. 
     The core  1218  may be formed of selected materials, such as non-magnetic materials. Further, the core  1218  may be formed of two or more components including an internal metallic (e.g. metal or metal alloy) component and an external non-conductive sheath on which the windings  1216  are formed or placed. In various embodiments, due to a current through wire that forms the windings  1216  thermal energy may be generated. It is understood, however, that the windings  1216  may be formed of a metallic or non-metallic wire or other appropriate material. In various embodiments, the windings  1216  are formed of a copper wire. 
     Thermal energy within or at the stator  120  may be dissipated according to various embodiments, such as a flow of air, or airflow, over or through the windings  1216 . The airflow may be caused or provided due to the one or more openings or throughbores  106  formed in the crank case  100 . The crank case  100  may include the openings  106  that allow the housing  1208  to be exposed to or receive external airflow, such as external from the engine assembly  40  and/or the snowmobile  10 . 
     The airflow may travel along an airflow path  1226  that is initiated or started external to the crank case  100  and passes through the openings  106 . The air that initiates or starts from external to the crank case  100  may be substantially cooler than air that is within the engine assembly  40 . Further the openings  106  may be formed in the crank case  100  at a position that is at or near a cool region of the engine assembly  40 . A cool region of the engine assembly may be a region that is substantially positioned away from heat sources or other hot air or thermal sources, such as an exhaust manifold, evaporation fins or passages, or the like. Further, the cool region may be near or at a riding surface (e.g. ground) and/or near the skis  20 . In various operating conditions, such as with snow cover on a riding surface, the riding surface may be substantially cooler than other areas. Thus, the region of the engine assembly  40  that is the coolest may be near the riding surface and away from heat sources, such as cylinders or exhaust manifold. 
     In various embodiments, as illustrated in  FIG.  4    and the other figures above, the openings  106 , also referred to as air vents or vent openings, may be positioned substantially at a side of the snowmobile  10  and near a bottom of the engine assembly  40 , and generally in a cool region of the engine assembly  40 , as noted above. In various embodiments, the openings  106  in the crank case  100  may be positioned substantially near a surface or area over which the snowmobile  10  is passing. Therefore, the air drawn through the vent openings  106  may be cooler than substantially any other air source or air volume adjacent or near the engine assembly  40 . 
     The airflow through the air vents or openings  106  may be caused by a fan portion or assembly  1228 . With continuing reference to  FIG.  23    and additional reference to  FIG.  6   , the fan assembly  1228  includes various features such as one or more cooling fins or veins  1230 . The fins  1230  extend from a surface or body  1232 . The fins  1230  may include an upper surface or contacting surface  1234 . The contacting surface  1234  may be near and/or contact a face or surface  1248  of the fly wheel  118 . The fan assembly  1228  may further include a contact or mounting surface  1236  from which the fins  1230  radially extend towards an outer edge or perimeter  1238  of the fan assembly  1228 . 
     The mounting surface  1236  may be substantially solid or include a central opening or aperture  1240 . The central aperture  1240  may be defined or formed by an interior wall  1242 . In addition, one or more through bores  1244  may be formed through the mounting surface  1236 . One or more mounting fasteners  1246 , such as bolts or rivets, may pass through the apertures  1244  and engage the fly wheel  118 . The fly wheel  118  may include the mounting surface or face  1248 . The mounting surface  1248  may include a fastening passage  1250  that may receive or threadably engage the fasteners  1246 . For example, the passages  1250  in the mounting face  1248  may be tapped or include threads to receive or engage the bolt  1246 . It is understood that other appropriate fastening members, however, may be provided or used to fix the fan assembly  1228  to the fly wheel  1248 . 
     Because the fan assembly  1228  is fixed to the fly wheel  118 , such as via the mounting face  1248 , the fan assembly  1228  rotates substantially in common or due to rotation of the fly wheel  118 . Accordingly, when the fly wheel  118  rotates, the fan assembly  1228  also rotates. Rotation of the flywheel  118  is caused by the drive shaft  102  connected to the fly wheel  118 . The engine assembly  40 , including the drive shaft  102 , therefore, causes rotation, and generally simultaneous rotation, of the flywheel  118  and the fan assembly  1228 . 
     Formed between or defined between two adjacent fins  1230  may be an airflow or pocket area  1254  that may cause airflow generally in the direction of the air-path  1226 , as illustrated in  FIG.  23   , and specifically in the direction of arrow  1226   a . The air-path  1226  initiates through the vent openings  106 , and passes through the stator  120 , such as between the winding  1216 . The air-path  1226  further continues through the magnetic ring  1212  that is positioned within the fly wheel  118 . The air-path  1226  further extends through one or more flywheel vents passages or throughbores  1256 . 
     The flywheel vent passages  1256  are formed in the mounting face  1248  and may not be the only passages through the fly wheel  118 . For example, the flywheel  118  may include a second wall or annular member  1257  that extends substantially perpendicular to the face  1248 . The second wall  1257 , when assembled in the engine assembly  40 , may encompass or surround the stator  120 . Further, the second wall  1257  generally extends away from and one a side opposite the fan assembly  1228 . Alternatively or in addition to the vent passages  1256 , auxiliary or outer surface passages  1258  may be formed through the second wall  1257 . The rotation of the fan assembly  1228  may cause a low pressure on or near an outer face of the mounting face  1248 , generally in the downstream direction indicated by the air-path  1226 . 
     The rotation of the fan assembly  1228  may cause the airflow or a flow of air generally in the direction of air-path  1226  through the vent openings  1256  and through the pockets  1254  due to the fins  1230  and associated structure and geometry, such as opening of the pocket  1254  at the outer edge  1238  of the fan assembly  1228 . The air-path  1226 , therefore, continues toward an outer edge or outer circumference  1238  of the fan assembly  1228 . In other words, as illustrated in  FIG.  23   , the air-path  1226  may include a radial flow in the direction of arrow  1226   a  away from a central axis  1270  of the fan assembly  1228 . The fan assembly  1228  by rotating and having the pockets  1254  direct air flow away form an axis of rotation of the fan assembly  1228 . The pockets  1254 , therefore, may include an airflow exit or exit passage for the air that is being moved by the fan assembly  1228 . The flow may, therefore, not be straight and may move radially away from the center of the fan assembly and generally in a direction formed or defines by the pocket  1254 . This direction may also direct the air toward an outer edge of the cover  126 , as discussed herein. 
     The air-path  1226  may then pass through a vent opening  1262  in the cover  126 . Accordingly, the air-path  1226  is formed through the housing  1208  of the crank case  100  by the air vents  106 . The air-path  1226  passes through the stator  120 , the mounting face  1248  of the fly wheel  118 , past the fins  1230  of the fan assembly  1228 , and out through the vent passages  1262  of the cover  126 . The air flow along the air-path  1226  may be caused due to the fan assembly  1228 , such as with the fins  1230 , as discussed further herein. 
     With continuing reference to  FIG.  24    and additional reference to  FIGS.  25  and  26   , the fan assembly  1228  is discussed. The fan assembly  1228  may include an integrally formed recoil cup or holder  1264 . The recoil cup  1264  may include an outer circumferential wall  1266  that includes a selected geometry, such as an array of internal projections  1268 . The outer wall  1266  may engage a recoil assembly, such as pull cord recoil assembly, that may be used to initiate starting of the engine assembly  40 . It is understood, however, that the recoil assembly need not be incorporated into the fan assembly  1228 . For example, the fan assembly  1228  may include the fins  1230  and selected features, such as the surface member  1232 , mounted to the recoil cup  1264  to form an integrated fan assembly  1228 . In various embodiments, however, the fan assembly  1228 , including the fins  1230  and related structures, and the recoil cup  1264  form as separate and distinct members. In various embodiments, the fan assembly  1228  may be formed as a single piece a casting including the fan portions and the recoil cup  1264 . The single casting may be formed of a magnesium or magnesium alloy. The integrated or one piece casting may allow for a lightweight and substantially rigid structure to connect to the fly wheel  118 . Nevertheless, one skilled in the art will understand that the various portions of the fan assembly  1228  may be formed separately and connected together such as with brazing or welding during a manufacturing process. 
     The fan assembly  1228  including the fins  1230  may form a vacuum on a selected side of the fly wheel  118 , thereby causing air flow along the air-path  1226 , due to a construction of the fan assembly portion. As discussed above, the fins  1230  extend from a surface  1232 . The surface  1232  may be formed in the pocket  1254 , as illustrated in  FIG.  24   . In the pocket  1254 , a first region  1232 ′ of the surface  1232  may be closer to the mounting plate surface  1236  near a central or rotational axis  1270  of the fan assembly  1228  than an outer surface or region  1232 ″. The surface  1232 , therefore, may be sloped or formed at an angle  1272  relative to the axis  1270 . The angle  1272  of the surface  1232  may assist in forming, directing, or otherwise causing an airflow through the vent opening  106  and the crank case  100  and the passages  1256  of the fly wheel  118 . 
     In addition to the angle  1272  of the surface  1232 , the fins  1230  may include a curved or arcuate surface  1276 . The curved surface  1276  of the fins  1230  may be substantially c-shaped having an inner curved portion or inner surface  1276  and a back or second surface  1280  of an adjacent fin  1230 . 
     The pocket  1254  may be formed between the two surfaces  1276 ,  1280  and the surface  1232  between two adjacent fins  1230 . The pocket  1254  and the respective fins  1230 , including the surfaces  1276 ,  1280 , and the base surface  1232  form the fan structure of the fan assembly  1228  to cause airflow along the path  1226 . 
     Due to rotation of the fan assembly  1228 , by being mounted to the fly wheel  118 , the fan assembly  1228 , given the structure as discussed above, may cause the airflow along the air-path  1226 . Due to the airflow along the air-path  1226 , the stator  120  may be cooled by removing the thermal energy generated by the stator  120 , as discussed above. Thus, the stator  120  may be operated within a selected temperature range during operation of the engine assembly  40 . 
     In various embodiments, a shroud or seal member  1280  may also, optionally, be mounted in the engine assembly  40 . The shroud  1280  may be positioned to surround the fly wheel  118  and the mounted relative to the housing  1208  of the crank case  100 . The shroud  1280  may be fixed between the cover  126  and the housing  1208 . The shroud  1280  may have an internal opening  1282  that has a tight or close spaced tolerance relative to an outer surface  1284  of the fly wheel  118 . The tolerance or spacing between the inner surface  1282  of the shroud  1280  and the outer surface  1284  of the fly wheel  118  may be in the appropriate dimension such as about 0.01 millimeters (mm) to about 5 mm and further including about 0.5 mm to about 3 mm, and further including about 0.2 mm to about 2 mm. 
     The shroud  1280  may block all or substantially all airflow other than along the air-path  1226 . In other words, the shroud  1280  may stop or eliminate all or substantially all air flow around the shroud, other than through the stator  120 . The shroud  1280  may be selectively installed to direct more or all of the air flow over or past the stator  120 . Thus, as discussed herein, the shroud  1280  may be provided to increase efficiency of cooling of the stator  120  and other components of the engine assembly  40  by providing the selected airflow. 
     The shroud  1280  by being mounted to the housing  1208  and substantially covering the area between the housing  1208  and the surface  1284  of the fly wheel  118 , may cause or direct substantially all of the air flow along the air-path  1226  through the vent  106 , the stator  120 , the air passages  1256  of the fly wheel  118 , and through the air vents  1262  of the cover  126 . The shroud  128 , according to various embodiments, may increase a cooling efficiency and/or amount of cooling of the stator  120 . The shroud  1280 , when installed, may cause or assist in causing an increased cooling of about 2% to about 20%, further including about 5% to about 15%, and further including about 3% to about 5%. In various embodiments, a measured temperature change between including the shroud  1280  and not including the shroud  1280  may case a temperature change (i.e. decrease) of about 30 degrees Centigrade to about 5 degrees Centigrade, and further including about 5 degrees Centigrade to about 15 degrees Centigrade. 
     In various embodiments, a temperature differential was determined by placing a temperature sensor (e.g. a thermocouple) to measure a temperature at one or more of the windings  1216  of the stators  120 . The engine assembly  40  was run at about 7000 rotations per minute until a measured temperature stabilized. Under selected test conditions, such as those exemplary discussed above, a temperature with the shroud  1280  and the fan assembly  1228  assembled, according to various embodiments, was measured to be about 208 degrees Centigrade as compared to 219 degrees centigrade with only the fan assembly  1228  installed (i.e. without the shroud  1280 . 
     Accordingly the shroud  1280  may increase a cooling efficiency or effectiveness of the stator  120  with the fan assembly  1228 , if selected. It is understood, however, the shroud  1280  is not required, but may be included in the engine assembly  40 . According to various embodiments, the shroud  1280  may also be formed of appropriate materials including aluminum or aluminum alloys, magnesium or magnesium alloys, other metallic or metal alloys, and appropriate polymers. The shroud  1280 , according to various embodiments, therefore, directs or assists in directing airflow of the air-path  1226 . 
     Accordingly the fan assembly  1228  may operate with the engine assembly, such as being driven directly or indirectly by the driveshaft  120  to cause an airflow along the air-path  1226 . The airflow along the air-path  1226  may appropriately cool or provide a selected operating temperature of the stator  120 . The operating temperature of the stator  120  may, therefore, allow for efficient operation of the stator  120  and the associated electrical components of the snowmobile  10 , including the engine assembly  40 . 
     E. Vehicle Starter System and Method 
     Referring now to  FIG.  27   , a handheld/removable battery key module  1510  is removably coupled to the vehicle  1520 . The handheld/removable battery key module  1510  will be described in detail below. The handheld/removable battery key module  1510 , in general, may be a lithium ion battery that includes the function of a key to enable the engine to start. The battery portion of the handheld/removable battery key module  1510  is used for starting the vehicle. The battery key module  1510  has electrical terminals  1512 A- 1512 C, collectively, terminals  1512 . The terminals  1512  may be used for providing power to a starting actuator for starting the vehicle. The terminals  1512  may also be used for charging the battery cells in a home or remote charger located away from the vehicle  1520 . 
     Because the handheld/removable battery key module  1510  is handheld, portable or removable, the user of the vehicle  1520  may store the battery in a pocket or within a residence or other warm place so that the vehicle is easy to start using the handheld/removable battery key module  1510  that has an increased or higher temperature than that of the vehicle  1520 . In this regard, ambient body heat will maintain or increase the power that can be delivered by the lithium ion battery cells. 
     The vehicle  1520  may include a receptacle  1522  for receiving the handheld/removable battery key module  1510 . In fact, electrical terminals  1512  may couple to electrical terminals  1524  within the receptacle  1522 . An engine controller  1526  receives the signals from the electrical terminals  1524  and ultimately are used to power a starting actuator  1528  which starts the engine  1530 . The starting actuator  1528  may be a traditional starter motor that has a pinion gear engaging the crankshaft. The starting actuator  1528  may also power the stator with the battery key module  1510  to cause the stator to move back and forth and ultimately with fuel and spark cause the engine to start, as will be described further below. In general, once the engine controller  1526  verifies the identity of the handheld/removable battery key module  1510 , power may be provided to the starting actuator  1528  to start the engine  1530 . Details of the method for starting the engine  1530  are set forth in further detail below. Of course, various types and shapes of receptacles  1522  may be used for receiving the handheld/removable battery key module  1510 . The receptacle  1522  and the terminals  1512 A- 1512 C of the battery key module  1510  may be made to be weather resistant. 
     Referring now to  FIG.  28   , the engine controller  1526  is illustrated in further detail. The controller  1526  may be coupled to a start button  1540  located on the vehicle  1520  for starting the engine  1530 . Various vehicle inputs  1542  may be in communication with the controller  1526 . The vehicle inputs  1542  may depend upon the level of control desired, the type of vehicle and the various types of engines. In the present example, the engine  1530  may be a two-stroke engine. However, much of the teachings apply to a four-stroke engine as well. The vehicle inputs  1542  may include various sensors that provide signals for the speed of the vehicle and temperatures associated with the vehicle including the ambient temperature and the temperature of various fluids or air temperatures. The vehicle inputs  1542  may also include pressures such as intake pressures, exhaust pressures and the barometric pressure around the vehicle. 
     The vehicle  1520  may also have crankshaft position sensors  1544 A and  1544 B, such as the crankshaft position sensors  122  discussed above, coupled to the controller  1526 . The crankshaft position sensors  1544 A and  1544 B allow the controller  1526  to time various events within the vehicle including the timing of the operation of the spark plugs  1546 , such as spark plugs  70  described above, and the fuel system  1548  which may include the fuel pump  1550  and the fuel injectors  1552 , such as the fuel injectors  86 , as described above. Depending on the system, one or two crankshaft position sensors  1544  may be used. In the example set forth below, two crankshaft position sensors  1544  are provided. The crankshaft position sensors  1544  may be Hall effect sensors that sense the edges of the steel teeth on the flywheel. 
     The engine controller  1526  includes various modules including a fuel control module  1560 , an engine position sensing module  1562  which may include a direction sensing module  1564  for sensing the direction of the rotation of the crankshaft based upon the crankshaft position sensors  1544 A and  1544 B as will be described in detail below. The engine controller  1526  may also include a spark control module  1564  for controlling the timing of the spark generated at the spark plugs  1546 . 
     The engine controller  1526  may also include an identifier determination module  1566  that is used to determine the identity and compare the identity provided from the handheld/removable battery key module  1510 . Details of the actions of the identifier determination module  1566  will be described below. 
     The engine controller  1526  may also include a proximity module  1568 . The proximity module may be used to determine the proximity of the handheld/removable battery key module  1510  to the vehicle to initiate the starting of a heater to heat the battery cells within the handheld/removable battery key module  1510 . The actions of the proximity module  1568  will also be described in further detail below. 
     Referring now to  FIG.  29   , the handheld/removable battery key module  1510  is illustrated in perspective view. A connector  1570  may include the electrical terminals  1512  for coupling to the vehicle. The handheld/removable battery key module  1510  may be sized to fit within a jacket pocket. For example, the size may be 5×2.8×5 inches. Other features such as a light  1572  and a charging point  1574  may be coupled thereto. A manual button  1576  may be used to manually power and depower the heater to warm the battery cells. 
     Referring now to  FIG.  30   , a block diagrammatic view of the handheld/removable battery key module  1510  is illustrated in further detail. The handheld/removable battery key module  1510  may include a temperature sensing module  1580 . The temperature sensing module  1580  may be coupled to a heater control module  1582 . The temperature sensing module  1580  may sense the ambient temperature at the handheld/removable battery key module  1510  and control the heater control module  1582  should the temperature drop below a predetermined temperature threshold. 
     An interface module  1584  may provide electrical terminals that interface with electrical terminals within a vehicle or within a receptacle of the vehicle as described above. The interface module  1584  may also be used for communicating a key identifier or code from an identity module  1586  to the vehicle for security purposes when the handheld battery key module identifier corresponds to a saved identifier within the engine controller  1526 . 
     A charging module  1588  may be coupled to battery cells  1590 . The charging module  1588  may be used for charging the battery cells and monitoring the state of charge of the battery cells. The interface module  1584  may be used to provide power from an outside source for charging the battery cells  1590  until the control of the charging module  1588 . 
     A control module  1592  is shown in communication with a memory  1594 . The control module  1592  may be a microprocessor based control module or an application specific integrated circuit for controlling the various functions within the battery key module  1510 . The interconnection of the control module  1592  with the various modules within the battery key module  1510  are not shown for simplicity. 
     A lighting module  1596  may also be coupled to battery cells  1590  to provide a flashlight function for convenience. 
     Referring now to  FIG.  31   , a detailed schematic view of the battery key module  1510  is illustrated. The battery key module  1510  is shown in relation to the vehicle  1520 . As mentioned above, the receptacle  1522  may be used for coupling the vehicle  1520  with the battery key module  1510 . A plurality of resistors are provided in series. The resistors are heating elements and correspond to the battery cells C 1 -C 4 . That is, resistor R 1  corresponds to battery cell C 1 , resistor R 2  corresponds to battery cell C 2 , resistor R 3  corresponds to battery cell C 3 , and resistor R 4  corresponds to battery cell C 4 . The battery cells C 1 -C 4  may be made of various chemistries including lithium ion. A power transistor Q 1  is used for controlling the elements. A power transistor Q 1  is coupled to the series connection of the resistors R 1 -R 4 . The power transistor is also coupled to a HEATER CONTROL pin. A temperature sensor TR 1  is coupled to a TH positive input and a TH negative input of the control module  1600 . The temperature sensor TR 1  is used to sense the temperature within the battery key module  1510 . Battery power is provided to the control module  1600  through a VBAT pin. The battery voltage is provided to the resistor R 1  and to the terminal  1512 A. The terminal  1512 B is coupled to a SENSE input of the control module  1600 . The SENSE terminal may be in communication with the vehicle  1520  to provide a key identifier or a security code thereto. In the present example, the resistor R 5  may be a fixed resistor that is sensed by the engine controller  1526  of the vehicle. A second resistor R 6  used as a pullup resistor may be coupled between the battery terminal  1512 A and the SENSE terminal  1512 B. The resistor R 5  may be a fixed resistor and one of several values to produce a different key. If a resistor R 5  is not used, an electronic digital code may be communicated through the SENSE terminal  1512 B. 
     The control module  1600 , the battery cell C 4 , the resistor R 5  and a ground terminal GND may all be coupled to ground or common through the terminal  1512 C. 
     Referring now to  FIG.  32   , a method of starting the vehicle using the handheld/removable battery key module  1510  is set forth. In step  1610 , an optional step of bringing the key within a proximity of the vehicle may be performed. The proximity of the vehicle will be sensed in various ways including an electrical field that is sensed at the controllers  1526  by the proximity module  1568 . Another optional step  1612  may also be performed. In step  1612 , the battery temperature is sensed. As mentioned above, a temperature sensor TR 1  may be used to sense the battery temperature. In step  1614 , if the battery temperature is less than a temperature threshold, in step  1616  the battery heater is powered by the battery cells of the removable battery key module. The battery heater corresponds to resistors R 1 -R 4  of the handheld/removable battery key module  1510 . To control the heating of the resistors, the switch Q 1  may be operated. 
     Step  1618  may be performed when the temperature of the battery is not less than the temperature threshold or after step  1616 . In step  1618 , the battery key module is coupled to the vehicle. That is, the terminals  1512  may be coupled to the terminals  1524  in the receptacle  1522  as described above. In step  1620 , the start button  1540  of the vehicle may be engaged. In step  1622 , the key identifier of the identity module  1586  of the battery key module  1510  is read by the engine controller  1526 . If the key identifier matches the identifier stored within the engine controller  1526 , step  1624  determines whether the key identifier is correct. The vehicle  1520  is prevented from starting in step  1626  if the key identifier is not correct. In step  1624 , if the key identifier is correct, the vehicle  1520  is started in step  1628 . As will be mentioned further below, starting the vehicle  1520  may entail powering a starting actuator to rotate the crankshaft and providing fuel and spark to the engine  1530 . 
     Referring now to  FIG.  33   , a perspective view of a flywheel  1650  is illustrated. In this example, the flywheel  1650  has two tracks Track  1  and Track  2 . Track  1  is axially spaced apart from Track  2  on the outside of the flywheel  1650 . Track  1  comprises a first plurality of teeth  1652  spaced unequally around the circumference of the flywheel  1650 . Track  2  comprises a second plurality of teeth  1654  also spaced unequally on the outside of the flywheel  1650 . The teeth  1652 ,  1654  in both tracks comprise steel teeth which are illustrated as raised surfaces which are picked up by crankshaft position sensors  1544 . The crankshaft position sensors  1544 A and  1544 B are located directly adjacent to each of the respective tracks, Track  1  and Track  2  to sense the teeth  1654 . 
     Referring now to  FIG.  34   , a view of the first track Track  1  and the second track Track  2  and the teeth  1656  associated therewith are set forth in a linear manner relative to the position of the crankshaft. In this example, there are two cylinders, a first cylinder Cylinder  1  having a top dead center at 75 degrees and a second cylinder Cylinder  2  having a top dead center at 255 degrees. In the present example, twelve pole pairs  1656 A- 1656 F are set forth. Each of the poles are 30 degrees of rotation of the crankshaft wide. In the present example, the top dead center position of the first cylinder has a width W 1  which is less than the width W 2  of the remaining teeth  1652 B- 1652 D. Likewise, Track  2  tooth  1654 A has the same width W 1  as tooth  1652 A. Teeth  1654 B- 1654 D have the same width W 2 . It should be noted that tooth  1652 A and  1654 D from the respective first track and second track align with top dead center of Cylinder  1 . Teeth  1652 D and  1654 A align with top dead center of Cylinder  2 . In the present example, there are several geometric relationships of the teeth. The wider teeth are 180 degrees divided by P wide, where P is the pole count. The wide teeth are aligned with the north poles of the flywheel. The teeth of Track 1  are between the top dead center of Cylinder  1  and top dead center of Cylinder  2  as the flywheel is rotated in a forward direction. That is, between 75 degrees and 255 degrees on center, Track  2 &#39;s teeth are between 255 degrees and 75 degrees of the next rotation of the crankshaft. The position of the narrower teeth  1652 A and  1654 A may be set at a desired position before top dead center to provide optimal operation based upon experimentation. In the present example, the narrow tooth or Width W 1  is 15 degrees wide centered at top dead center. Also in the present example, the forward direction of the crankshaft is to the right as indicated by the increase in degrees as at the top of  FIG.  34   . Because the engine is always started in the forward direction, the first sensed tooth leading edge determines the next piston to reach top dead center. The crank direction is determined after each top dead center event. The combination of the last top dead center position and the track of the next leading edge detection determines the direction. 
     Referring now to  FIG.  35   , a chart illustrating the leading edge of Tracks  1  and  2  and the top dead center of Cylinder  1  and Cylinder  2  are used for direction determination. For Cylinder  1 , a forward direction is determined if Track  1  is sensed or a reverse direction if Track  2  is sensed. For Cylinder  2 , a reverse direction is determined when the top dead center of Track  1  is detected and the forward direction is determined when the top dead center of Track  2  is detected. 
     Referring now to  FIG.  36    and  FIGS.  37 A- 37 C , in step  1670 , fuel is injected into the closed intake port  1710  by a fuel injector  1552  disposed in a fuel injector port  1711 . A starting actuator  1528  is electrically energized in step  1672 . As mentioned above, a starter motor or other starting apparatus may be energized from the handheld/removable battery key module  1510  described above. In step  1674 , the pistons  1712  are disposed within the cylinder  1714 . By rotating the crankshaft  1718  connected to the connecting rod  1716  counterclockwise or in a first direction, the intake port  1710  to the cylinder  1714  is open in step  1676 . This is illustrated in  FIG.  27 B . The crankshaft  1718  is then rotated in the forward direction, clockwise or first direction at step  1678 . At step  1678 , the crankshaft  1718  is reversed in direction without passing top dead center using the starting actuator. These are indicated by the feedback from the plurality of teeth as set forth in  FIG.  34   . The air/fuel mixture admitted into the cylinder is then compressed in step  1680 . In step  1682 , the air/fuel mixture is ignited using the spark plug  1546  to propel the crankshaft  1718  to continue along the forward direction. This is illustrated in  FIG.  37 C . In step  1684 , the crankshaft  1718  is rotated in a forward direction and the engine is fully started. 
     F. Fuel Management System and Method 
     Referring now to  FIG.  38   , a simplified view of an engine  1810  is illustrated. The engine  1810  may be a two-stroke engine. However, teachings set forth herein may also apply to a four-stroke engine. The engine  1810  may be applied to various types of vehicles including but not limited to side-by-side vehicles, motorcycles and snowmobiles. The following disclosure is particularly suitable for snowmobiles. 
     The two-stroke engine  1810  is shown in a simplified view with a starting apparatus  1812  coupled thereto. The starting apparatus  1812  may include a battery starter, a pull starter or a stator for starting. 
     An exhaust valve  1813  or guillotine is used to control the size of the exhaust port. The position of the valve is controllable by way of an engine controller  1820 . 
     The two-stroke engine  1810  may also include fuel injectors  1814 , such as the fuel injectors  86  illustrated above. The fuel injectors  1814  operate to provide a pulse of fuel to the cylinders of the engine. The fuel injectors  1814  operate using an electrical pulse that has a pulse width that lasts for a duration of time. The duration corresponds directly to the amount of fuel injected to the engine. The air fuel mixture is drawn into a cylinder. Spark plugs  1816 , such as the spark plugs  70  illustrated above, are used to ignite the air fuel mixture within the cylinder. 
     The engine control unit or controller  1820  is coupled to various sensors  1822  for controlling the combustion functions of the engine  1810  by controlling the fuel injectors  1814  and the spark plugs  1816 . A fuel pump  1818 , such as the fuel pump  112  illustrated above, is used to pressurize a fuel line  1819  and communicate fuel from the gas tank to the engine. 
     The sensors  1822  coupled to the engine controller  1820  provide various signals that are used for controlling the combustion processes in the engine  1810 . The sensors  1822  include an air pressure sensor  1830  which generates an air pressure signal corresponding to the barometric pressure to the engine controller  1820 . 
     A housing  1832  may include both a fuel pressure sensor  1834  and a fuel temperature sensor  1836 . The fuel pressure sensor  1834  generates a fuel pressure signal corresponding to the pressure in the fuel line  1819 . The fuel temperature sensor  1836  generates a signal corresponding to the fuel temperature within the fuel line  1819 . The housing  1832 , and thus both sensors, may be coupled to the fuel line  1819  leading to the engine  1810 . 
     An engine speed sensor  1838  is also coupled to the controller  1820 . The engine speed sensor  1838  generates a signal corresponding to the rotational speed of the engine. The rotational speed may correspond to the rotation of the crankshaft which may be in rotations per minute. 
     A water temperature sensor  1840  may also be in communication with the engine controller  1820 . The water temperature sensor  1840  generates a signal corresponding to the coolant within the vehicle. Although the water temperature sensor  1840  is set forth as a “water” sensor, coolant such as ethylene glycol and other compounds may be used in place of or combined with water. 
     A throttle position sensor  1842 , such as the throttle position sensor  92  illustrated above, is also in communication with the engine controller  1820 . The throttle position sensor  1842  generates a signal corresponding to the throttle position. Typically, throttle position sensors are resistive in nature and provide an output voltage that corresponds to the throttle position as controlled by the vehicle operator. The throttle position sensor  1842  may correspond to the output of a floor-mounted pedal or a handle-mounted switch. 
     An exhaust valve position sensor  1844  may also be coupled to the engine controller  1820 . The exhaust valve position sensor  1844  provides an output of the exhaust valve “guillotine” position to the engine controller. The exhaust port open timing is controlled by the controller  1820 . 
     An exhaust gas temperature sensor  1846  provides a signal corresponding to the temperature of the exhaust gas. 
     An air temperature sensor  1848  generates a signal corresponding to the air temperature of air entering the engine. 
     The engine controller  1820  may have various modules used for adjusting the pulse width duration of the signal for controlling the fuel injectors. The electrical pulse width of the injectors corresponds to the amount of fuel injected into the engine with each pulse. As will be described in more detail below, a fuel injector pulse width determination module  1850  is used for determining the ultimate fuel injector pulse width used for each of the electrical pulses for the engine. The electrical pulses may vary based upon the various sensors input signals to the engine controller  1820 . The fuel injector pulse width determination module  1850  receives a plurality of correction factors by way of signals to determine the ultimate pulse width duration applied to the fuel injectors  1814 . 
     The fuel injection pulse width determination module  1850  receives signals from the initial injection control module  1852 . The initial injection control module  1852  is used to control the initial or first injection of fuel into the system. This is particularly important for use in a batteryless vehicle. The first injection of fuel is important. But, because certain vehicles do not have a battery, the first pull of the vehicle takes some time to raise the chassis voltage and turn the fuel pump on. As will be further described below, the initial injection control module  1852  may monitor the fuel pressure and delay the initial injection of fuel until the fuel pressure raises above a fuel pressure threshold. By preventing the fuel injector from receiving electrical power when not enough fuel pressure is available, the system prevents the fuel injector from using electrical power for starting the engine. Thus, the initial injection control module  1852  commands the fuel injector pulse width determination module  1850  to delay the operation of the fuel injector. 
     The fuel pressure correction module  1854  generates a fuel pressure correction factor for use in the fuel injection pulse width determination module  1850 . As will be further described below, the first injection of fuel is controlled by the initial fuel injection control module  1852 . Thereafter, the pulse width duration of the injector is corrected based upon the fuel pressure, the fuel temperature and the barometric pressure. Each of these processes will be described in the modules below. The initial injection control module  1852  is in communication with a first fuel table  1853  that provides a first fuel value based upon water temperature and fuel pressure. That is, the initial pulse width is determined from a two-dimensional table with an axis of fuel pressure and a second axis of engine water temperature. Thus, the first pulse width is a function of the fuel pressure and the engine water temperature. An example two-dimensional table is illustrated in  FIG.  39 A . The X values would be replaced with actual values using experimentation in the field or on a dynamometer. 
     The fuel pressure correction module  1854  uses a first pressure correction table  1856  and a second pressure correction table  1858  to perform corrections based upon the fuel pressure signal from the fuel pressure sensor  1834 . By controlling the duration of the pulse width based upon the fuel pressure, the fuel temperature and the barometric pressure, the system provides compensation to maintain stability margins at the edges of the operating range. As the vehicle operates in various altitudes, the stability at high elevations is maintained. Although two pressure correction tables  1856  and  1858  are illustrated, only one table may be provided. The table  1856  is a one-dimensional table that is used to replicate the pressure square root ratio correlation. The pulse width correction PW corr  is: 
     
       
         
           
             
               P 
               ⁢ 
               
                 W 
                 Corr 
               
             
             = 
             
               P 
               ⁢ 
               
                 W 
                 
                   B 
                   ⁢ 
                   a 
                   ⁢ 
                   s 
                   ⁢ 
                   e 
                 
               
               * 
               
                 
                   P 
                   
                     P 
                     
                       r 
                       ⁢ 
                       e 
                       ⁢ 
                       f 
                     
                   
                 
               
               * 
               
                 
                   
                     Trim 
                     ⁢ 
                     
                         
                     
                   
                   
                     ( 
                     
                       N 
                       , 
                       P 
                     
                     ) 
                   
                 
                 
                   1 
                   ⁢ 
                   0 
                   ⁢ 
                   0 
                 
               
             
           
         
       
     
     wherein the PW Base  is the base pulse width calculated from the engine rpms and throttle position, P is the measure fuel pressure, P ref  is the reference pressure and Trim is a desired amount of offset as a function of Pressure, P and the engine speed, N. Trim may be experimentally determined based on various operating engine speeds and pressures. 
     The second pressure correction table  1858  may take the form of a two-dimensional table having an access of the speed of the engine and fuel pressure. That is, a second pressure correction may have the ordinates of engine speed and the fuel pressure. The fuel pressure correction module provides a first correction from the pressure correction table  1  and the second pressure correction table  1858  to the fuel injector pulse width determination module  1850 . Fuel injector voltage may also be an ordinate. 
     A fuel temperature correction module  1860  receives a fuel temperature sensor signal from the fuel temperature sensor. The fuel temperature sensor signal provides a temperature corresponding to the fuel temperature within a fuel line of the vehicle. A temperature correction table  1862  provides a two-dimensional table for determining a temperature correction. The temperature correction table has an axis of engine speed in rpms and the fuel temperature as a second axis. Again, the temperature correction table may provide a temperature correction factor that is used by the fuel injection pulse width determination module  1850 . 
     A barometric pressure correction module  1870  is used for determining a barometric pressure correction. The barometric pressure correction module  1870  is used for setting a minimum floor for the pulse width duration. When the pulse width duration is below a predetermined pulse width duration, the barometric pressure correction table or authority table  1872  is used for determining a new injection pulse width duration in the place of the minimum. Previously, the minimum calculated pulse width duration was the cutoff. However, it has been found that if the final corrected duration is less than the minimum duration characteristic of the injectors, the engine controller may calculate a commanded duration which overrules the calculation and uses a calibratable minimum injection in its place. As illustrated in  FIG.  39 B , the injector flow has a linear region and a non-linear region. The linear region corresponds to an injection time below T min . In this area, the barometric pressure correction table  1872  may be calibrated based upon the barometric pressure to reduce the injector time below the previously calculated minimum. 
     Referring now to  FIG.  39 C , one example of the barometric pressure correction table  1872  is set forth. An authority is shown plotted against the barometric pressure. As the barometric pressure rises, the amount of the correction factor or authority value increases. The final pulse width T final  is equal to T c +A min (T min −T c ). 
     T c  is the previously determined minimum correction factor. The determination of this will be described in further detail below. 
     Referring now to  FIGS.  40 A and  40 B , the sensor housing  1832  is illustrated in further detail. That is, the sensor housing  1832  has both the fuel pressure sensor  1834  and the fuel temperature pressure  1836  illustrated in  FIG.  38   . A pull-up module  1880  may be disposed as a discrete component or as a component within the engine controller  1820 . The pull-up module  1880  includes a pressure pull-up resistor Rp which is coupled between the supply voltage V s  and the pressure voltage output signal P out . A temperature pull-up resistor R t  is coupled between the supply voltage V s  and the temperature voltage signal T out . A ground signal (GND) is also output from the pull-up module. 
     In  FIG.  40 B , the fuel line  1819  has an input  1882  and an output  1884  that passes fuel through the housing  1832 . A connector  1886  is used for connecting the sensor to the engine control module. 
     Referring now to  FIG.  41   , a method for operating an engine and determining pulse width is set forth. In step  1900 , the engine speed is determined. The engine speed may be determined in rotations per minute from the engine speed sensor  1838  illustrated above. In step  1902 , the throttle position is determined using the throttle position sensor  1842  illustrated in  FIG.  38   . In step  1904 , an exhaust valve position is determined. In step  1906 , a timing for base fueling T base  is determined using the engine speed, the throttle position sensor position and a valve position. In step  1907 , a water temperature is determined for the coolant within the engine. This may be performed using the water temperature sensor  1840  illustrated in  FIG.  38   . In step  1908 , a water temperature correction factor C wt  is determined. The water temperature correction factor C wt  is determined as a function of the water temperature and the speed of the engine. In step  1910 , the air temperature of the intake air to the vehicle is determined by the air temperature sensor  1848  illustrated in  FIG.  38   . The air temperature is the intake air temperature to the engine. In step  1912 , an air temperature correction factor C airtemp  is determined. The air temperature correction factor is based on the engine speed and the air temperature. In step  1914 , the barometric pressure around the vehicle is determined using the air pressure sensor  1830  illustrated in  FIG.  38   . In step  1916 , the barometric pressure correction factor C baro  is determined as a function of the barometric pressure and the engine speed. Each of the correction factors may be experimentally determined. 
     In step  1922 , a corrected duration T c  is determined where the base is multiplied by the correction factor of the water temperature, the air temperature correction factor, the barometric pressure correction factor and the exhaust gas temperature correction factor. In step  1924 , it is determined whether the corrected duration T c  is less than a minimum pulse width duration. If the correction duration is not less than the minimum, pulse width is set at T c  in step  1926 . 
     In step  1928 , the barometric pressure determined in step  1914  is used to determine a barometric pressure authority factor A min . This is performed using the barometric pressure correction table  1872  of  FIG.  38   . In step  1930 , a final pulse width duration T final  is determined using the formula described above in the barometric pressure correction module  1870 . 
     It should be noted that  FIG.  41    takes place during normal operation of the engine.  FIG.  8    uses the barometric pressure to change the minimum duration of the pulse width. 
     Referring now to  FIG.  42   , the steps set forth take place during the initial starting of the engine and to correct for fuel and temperature pressure. In step  1940 , starting is initiated. As mentioned above, starting may be initiated using a battery or pull starting the engine. In step  1942 , it is determined whether the system is injecting the first pulse upon start-up. As the system becomes energized, the engine controller, the fuel pump and the injectors are becoming energized. The energization of the fuel injectors may be suppressed before the first pulse. This prevents the fuel injectors from using electrical power. In step  1946 , the fuel pressure is determined using the fuel pressure sensor  1834 . In step  1948 , it is determined whether the measured fuel pressure is greater than a reference pressure. If the measured pressure from step  1946  is not greater than the reference pressure. The fuel injector is prevented from activating in step  1950 . After step  1950 , step  1946  is performed. 
     In step  1948 , when the measured pressure is greater than the reference pressure, the first pulse is allowed in step  1950 . In step  1952 , the first pulse width is determined based upon the water temperature and the fuel pressure from the first fuel table  1853  illustrated in  FIG.  38   . In step  1954 , the fuel pressure is measured. Step  1954  is also performed after the pulse is not the first pulse in step  1942 . That is, after step  1942 , the engine is started and the initial steps  1946 - 1952  do not need to be performed. 
     In step  1956 , a two-dimensional correction factor based on the fuel pressure is determined based on the fuel pressure. This is obtained from the pressure correction table  1856 . In step  1958 , a one-dimensional pressure correction actor is also obtained from the pressure correction table  1858 . In step  1960 , the fuel temperature is measured. In step  1962 , the temperature correction factor is determined from the temperature correction table  1862 . In step  1964 , the final pulse width is determined based upon the temperature correction factor and the pressure correction factor as determined above. 
     Among the advantages of delaying the start pulse is the better perception of quality of the engine starting process by the consumer. Better control is had by monitoring the furl temperature and pressure. The pistons run cooler and thus the life of the engine is increased. 
     Examples are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of examples of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that examples may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some examples, well-known processes, well-known device structures, and well-known technologies are not described in detail. 
     The foregoing description has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular example are generally not limited to that particular example, but, where applicable, are interchangeable and can be used in a selected example, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.