Patent Publication Number: US-7900733-B2

Title: Motorcycle

Description:
RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 USC 119 of Japanese patent application no. 2008-083232, filed on Mar. 27, 2008, which is hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a motorcycle. 
     2. Description of Related Art 
     JP-A-Hei 10-297364 describes a motorcycle with a switch for regulating start-up of an engine. As a structure to regulate the start-up of the engine, the motorcycle in JP-A-Hei 10-297364 includes a brake lever, a switch case, a swing plate, a pushrod, and a switch corresponding to actuation of the pushrod. The brake lever actuates the swing plate. The swing plate actuates the pushrod. The pushrod actuates the switch. 
     In order to operate the above structure, a rider first pulls the brake lever. Corresponding to the brake lever operation, the swing plate makes a given rotation on a fixed position and pushes the pushrod. This allows the pushrod to actuate and turn on the switch. Once the switch is on, the motorcycle comes into a state where the engine can be started. 
     However, the switch does not regulate the engine speed after the engine has started and before the motorcycle starts moving. Thus, when the rider lets the engine to idle, it causes a problem of wasted fuel consumption. 
     SUMMARY OF THE INVENTION 
     The present invention addresses this problem and provides a motorcycle that reduces fuel consumption. 
     A motorcycle according to the present invention includes: an engine; a drive wheel driven by engine torque; a centrifugal clutch for intermittently transferring torque from the engine to the drive wheel in accordance with the engine speed; a switch for regulating engine speed; an engine start inhibition section for inhibiting start-up of the engine when the switch is off; and an engine speed regulation section for regulating the engine speed to prevent engagement of the centrifugal clutch when the switch is on. 
     As described above, with the present invention, fuel consumption of the motorcycle is reduced. 
     Other features and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawings that illustrate, by way of example, various features of embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view of a motorcycle according to an embodiment of the present invention. 
         FIG. 2  is a side view showing actuation of a cushion unit according to the embodiment of the present invention. 
         FIG. 3  is a plan view showing positional relationships among a body frame, an engine unit, an air chamber, and the like. 
         FIG. 4  is a sectional view taken along line IV-IV of  FIG. 1  showing positional relationships among a main frame, a rear arm, the air chamber, and the like. 
         FIG. 5  is a right side view of the engine unit. 
         FIG. 6  is a left side view of the engine unit. 
         FIG. 7  is a cross-sectional view showing a mounting state of the engine unit. 
         FIG. 8  is a cross-sectional view showing internal structure of the engine unit. 
         FIG. 9  is a cross-sectional view showing a portion of the internal structure of the engine unit. 
         FIG. 10  is an exploded perspective view of a second case block and an inner case of a transmission case. 
         FIG. 11  is a cross-sectional view of the insides of the second case block and the transmission case. 
         FIG. 12  is a cross-sectional view showing a portion of the internal structure of the engine unit. 
         FIG. 13  is a side view of the motorcycle according to the embodiment with a cover being removed, and shows an upright state of a main stand. 
         FIG. 14  is a side view of the motorcycle according to the embodiment with the cover being removed, and shows a stored state of the main stand. 
         FIG. 15  is a exploded perspective view of a body frame showing a main stand switch according to the embodiment. 
         FIG. 16  is a schematic structural view of a steering handle portion. 
         FIGS. 17A-17C  show a portion of a left handlebar. 
         FIGS. 18A and 18B  show a portion of the left handlebar and a state that a brake lock interlock switch is temporarily secured. 
         FIG. 19  is a control system diagram of the motorcycle according to the embodiment. 
         FIG. 20  is a flow chart showing engine speed regulation control, engine start inhibition control, and engine operation inhibition control according to the embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention is now described in detail with reference to the drawings. As shown in  FIG. 1 , a straddle-type vehicle according to this embodiment is a motorcycle  10 . The motorcycle  10  includes a body frame  11  defining a framework thereof and a seat  16  for a rider to be seated. Motorcycle  10  is a so-called moped type. In other words, the motorcycle  10  is formed with a concave space  17  in a side view, which is depressed downwardly, in front of the seat  16 , and a rider seated on the seat  16  straddles the body frame  11 . Here, the term “moped type” simply indicates a type of vehicle configuration, and does not limit the top speed, displacement, size, or the like of the vehicle in any way. 
     The straddle-type vehicle according to the present invention is not limited to the so-called moped type, and may be a different type of motorcycle such as one having a fuel tank in front of the seat. 
     In the following description, the terms “front”, “rear”, “right”, and “left” refer to directions as viewed from the rider seated on the seat  16 . The body frame  11  includes a steering head pipe  12 , a main frame  13  extending obliquely downward to the rear from the steering head pipe  12 , left and right seat rails  14 L,  14 R extending obliquely upward to the rear from a midsection of the main frame  13 , and left and right seat pillar tubes  15 L,  15 R connected to a rear end of the main frame  13  and also connected respectively to midsections of the seat rails  14 L,  14 R. 
     A body cover  21  covers the upper side and lateral sides of the body frame  11 . The concave space  17  in a side view, which is depressed downwardly, is defined above the body cover  21  and in front of the seat  16 . In addition, a center tunnel  11   a  is defined under the body cover  21  as a passage of the main frame  13 . 
     A front wheel  19  is supported by the steering head pipe  12  via front forks  18 . A fuel tank  20  and the seat  16  are supported on the seat rails  14 L,  14 R. The seat  16  extends from a position above the fuel tank  20  toward rear ends of the seat rails  14 L,  14 R. The fuel tank  20  is disposed on front-halves of the seat rails  14 L,  14 R, and is covered with the body cover  21  and the seat  16 . 
     A left and right pair of first engine brackets  22 L,  22 R protrudes downward from the midsection of the main frame  13 . The rear end of the main frame  13  is provided with a left and right pair of second engine brackets  23 L,  23 R and a left and right pair of rear arm brackets  24 L,  24 R. The brackets provided on the main frame  13  and the like, more specifically, the first engine brackets  22 L,  22 R, the second engine brackets  23 L,  23 R, and the rear arm brackets  24 L,  24 R constitute a part of the body frame  11 . 
     As shown in  FIG. 3 , a rear arm  25  includes a left and right pair of arm sections  25   a  and a coupling section  25   b  for coupling the arm sections  25   a  to each other. A front end of each arm section  25   a  is provided with a pivot section  25   c  through which a pivot shaft  38  is inserted. 
     The rear arm brackets  24 L,  24 R protrude downward from the rear end of the main frame  13 . As shown in  FIG. 4 , rear arm brackets  24 L,  24 R are provided with a pipe  24   a . The pivot shaft  38  passes through pipe  24   a  as well as the pivot sections  25   c . In this embodiment, the pivot shaft  38  is constituted by a long bolt, and the left end of the pivot shaft  38  is secured with a nut  38   b . This allows the rear arm  25  to be swingably supported at its front end by the pivot shaft  38 . A rear wheel  26  is supported at a rear end of the rear arm  25 . A rear half of the rear arm  25  is suspended by the body frame  11  via a cushion unit  27 . 
     As shown in  FIG. 7 , the second engine brackets  23 L,  23 R protrude downward from the rear end of the main frame  13 . Second engine brackets  23 L,  23 R face each other with a distance therebetween in a vehicle width direction. 
     As shown in  FIG. 1 , an engine unit  28  for driving the rear wheel  26  is supported by the body frame  11 . More specifically, as shown in  FIG. 6 , the engine unit  28  includes a crankcase  35 , a cylinder  43 , and a cylinder head  44 . The crankcase  35  has first and second engine mounts  36 ,  37 . The first engine mount  36  protrudes upward from the top at the front end of the crankcase  35 , and is supported by the first engine brackets  22 L,  22 R. The second engine mount  37  protrudes obliquely upward to the rear from the upper side at the rear end of the crankcase  35 , and is supported by the second engine brackets  23 L,  23 R (also see  FIG. 7 ). Thus, the crankcase  35  is supported by and suspended from the main frame  13 . 
     As the detail will be described later, the engine unit  28  includes an engine  29  and a belt-type continuously variable transmission (hereinafter referred to as CVT)  30  (see  FIG. 8 ). The type of the engine  29  is not limited in any way; however, in this embodiment, the engine  29  is a four-stroke single-cylinder engine. 
     As shown in  FIG. 1 , the motorcycle  10  has a front fender  31  for covering the upper side and the rear side of the front wheel  19 , and a rear fender  32  for covering the obliquely upper side at the rear of the rear wheel  26 . 
     In addition to the body cover  21 , the motorcycle  10  includes a front fairing  33  and left and right leg shields  34 L,  34 R. The leg shields  34 L,  34 R are cover members for covering front parts of the rider&#39;s legs, and extend obliquely in a vertical direction. 
     As shown in  FIG. 3 , each of the leg shields  34 L,  34 R has a concave shape that opens rearward in a horizontal cross section. In other words, each of the leg shields  34 L,  34 R is generally C-shaped and tapered forwardly in a cross section. 
     As shown in  FIGS. 2 and 4 , an air chamber  154  is disposed above a front portion  25   f  of the right arm section  25   a  of the rear arm  25 . Here, the front portion  25   f  of the arm section  25   a  indicates a portion in front of the midsection of the arm section  25   a  in a longitudinal direction. 
     An intake duct  153  is connected to the air chamber  154 . A portion of the intake duct  153  on the air chamber  154  side is also disposed above the front portion  25   f  of the arm section  25   a  of the rear arm  25 . However, the intake duct  153  may be deviated from a position above the front portion  25   f  of the arm section  25   a . In addition, a major part of the intake duct  153  may be situated above the front portion  25   f  of the arm section  25   a.    
     As shown in  FIG. 2 , a suction duct  156  is provided on the air chamber  154 . The suction duct  156  is constituted by a curved pipe, and an intake port  157  of the suction duct  156  opens obliquely downward to the front. However, no limitation is imposed on the opening direction of the intake port  157 . The intake port  157  may open forward, obliquely upward to the front, or in other directions. A filter  155  is accommodated in the air chamber  154 . 
     As shown in  FIG. 1 , the upper right side of the air chamber  154  and the right side of the suction duct  156  are covered with the cover  160 . The cover  160  covers a portion of the main frame  13  and that of the seat pillar tube  15 R from the side, and is a separate member from the body cover  21  that covers the seat rails  14 L,  14 R. However, the cover  160  and the body cover  21  can be integrated as long as they do not interfere with downsizing of the vehicle in the vehicle width direction. In other words, the cover  160  may be a part of the body cover  21 . 
     As shown in  FIG. 3 , footrests  85 L,  85 R made of rubber or the like are disposed on the left and the right of the engine unit  28 . The footrests  85 L,  85 R are supporting members on which the rider places his/her feet and are supported by the crankcase  35  of the engine unit  28  via a coupling rod  87  that is made of metal and a mounting plate  88  fixed to the coupling rod  87  (see  FIGS. 5 and 6 ). 
     The coupling rod  87  passes below the rear half of the crankcase  35  and extends in the vehicle width direction. The left end of the coupling rod  87  protrudes from the left side of the crankcase  35  and supports the left footrest  85 L. The right end of the coupling rod  87  protrudes from the right side of a transmission case  53  and supports the right footrest  85 R. As shown in  FIG. 5 , the mounting plate  88  is formed by pressing a metal plate, and a recess  89  to which the coupling rod  87  is fitted is formed in the midsection of the mounting plate  88  in the longitudinal direction. The recess  89  is abutted on the coupling rod  87  from below, and is welded to the peripheral surface of the coupling rod  87 . 
     The mounting plate  88  has a flange-like first mounting portion  90  that protrudes in front of the coupling rod  87  and a flange-like second mounting portion  91  that protrudes to the rear of the coupling rod  87 . The first mounting portion  90  and the second mounting portion  91  extend in an axial (left and right) direction of the coupling rod  87 , and face a bottom surface  83  in the rear half of the crankcase  35 . 
     The bottom surface  83  in the rear half of the crankcase  35  has four bosses  92  (only two are shown in  FIG. 5 ). Bosses  92  protrude downward from the bottom surface  83  of the crankcase  35 , and are formed integrally with the crankcase  35 . A bolt hole is formed in each of the bosses  92 . The mounting plate  88  of the footrests  85 L,  85 R is also formed with bolt holes in positions corresponding to the bosses  92 . The mounting plate  88  and the bosses  92  are fastened by bolts  99 . The footrests  85 L,  85 R are fixed to the crankcase  35  by the bolts  99  via the coupling rod  87  and the mounting plate  88 . 
     The internal structure of the engine unit  28  is now described. As shown in  FIG. 8 , the engine unit  28  includes the engine  29 , the CVT  30 , a centrifugal clutch  41 , and a deceleration mechanism  42 . 
     The engine  29  includes the crankcase  35 , the cylinder  43  connected to the crankcase  35 , and the cylinder head  44  connected to the cylinder  43 . The crankcase  35  is split into a first case block  35   a  located on the left and a second case block  35   b  located on the right. The first case block  35   a  and the second case block  35   b  are abutted on each other along the vehicle width direction. 
     A crankshaft  46  is accommodated in the crankcase  35 . The crankshaft  46  extends in the vehicle width direction, and is situated horizontally. The crankshaft  46  is supported by the first case block  35   a  via a bearing  47 , and is also supported by the second case block  35   b  via a bearing  48 . 
     A piston  50  is slidably inserted in the cylinder  43 . The piston  50  is coupled to an end of a connecting rod  51 . A crankpin  59  is provided between a left crank arm  46   a  and a right crank arm  46   b  of the crankshaft  46 . The other end of the connecting rod  51  is coupled to the crankpin  59 . 
     The cylinder head  44  is formed with a recess  44   a  and intake and exhaust ports that communicate with the recess  44   a . A spark plug  55  is inserted in the recess  44   a . As shown in  FIG. 5 , an intake pipe  52   a  is connected to the intake port, and an exhaust pipe  52  is connected to the exhaust port. As shown in  FIGS. 1 and 3 , the exhaust pipe  52  extends rearward and obliquely downward from the cylinder head  44  to the right, then passes below the transmission case  53  of the engine unit  28 , further extends rearward, and is connected to a muffler  54  disposed on the right side of the rear wheel  26 . 
     As shown in  FIG. 8 , a cam chain chamber  56  is formed in a left portion of the cylinder  43  to connect the inside of the crankcase  35  with that of the cylinder head  44 . A timing chain  57  arranged in the cam chain chamber  56  is wound around the crankshaft  46  and a camshaft  58 . The camshaft  58  rotates in accordance with the rotation of the crankshaft  46 , and opens and closes an intake valve and an exhaust valve. 
     A generator case  66  for housing a generator  63  is detachably attached to the left side of a front half of the first case block  35   a . The transmission case  53  for housing the CVT  30  is attached to the right side of the second case block  35   b.    
     An opening is formed on the right side of a rear half of the second case block  35   b  and is blocked by a clutch cover  60 . The clutch cover  60  is detachably fixed to the second case block  35   b  by a bolt  61  (see  FIG. 9 ). 
     The transmission case  53  is formed independently from the crankcase  35 , and is constituted by an inner case  53   a  for covering the inner (left) side of the CVT  30  in the vehicle width direction and an outer case  53   b  for covering the outer (right) side of the CVT  30  in the vehicle width direction. The inner case  53   a  is attached to the right side of the crankcase  35 . The outer case  53   b  is attached to the right side of the inner case  53   a . A belt chamber  67  for housing the CVT  30  is formed inside the inner case  53   a  and the outer case  53   b.    
     As shown in  FIG. 8 , the right end of the crankshaft  46  extends through the second case block  35   b  and the inner case  53   a  to the belt chamber  67 . A primary sheave  71  of the CVT  30  is fitted on the right end of the crankshaft  46 . Therefore, the primary sheave  71  rotates in accordance with the rotation of the crankshaft  46 . A right portion of the crankshaft  46  (a portion on the right side of the bearing  48 ) forms a primary sheave shaft  46   c.    
     The left end of the crankshaft  46  extends through the first case block  35   a  to the inside of the generator case  66 . A generator  63  is mounted on the left end of the crankshaft  46 . The generator  63  includes a stator  64  and a rotor  65  facing the stator  64 . The rotor  65  is fixed to a sleeve  74  that rotates along with the crankshaft  46 . The stator  64  is fixed to the generator case  66 . 
     A secondary sheave shaft  62  is disposed in parallel with the crankshaft  46  in the rear half of the crankcase  35 . As shown in  FIG. 9 , the secondary sheave shaft  62  is supported in the right side of its midsection by the clutch cover  60  via a bearing  75 . The secondary sheave shaft  62  is supported in the left side of its midsection by a left end portion of the second case block  35   b  via a bearing  76 . The right end of the secondary sheave shaft  62  extends through the second case block  35   b  and the clutch cover  60  to the belt chamber  67 . A secondary sheave  72  of the CVT  30  is coupled to the right end of the secondary sheave shaft  62 . 
     As shown in  FIG. 8 , the CVT  30  includes the primary sheave  71 , the secondary sheave  72 , and a V-belt  73  that is wound around the primary sheave  71  and the secondary sheave  72 . As mentioned above, the primary sheave  71  is mounted on the right portion of the crankshaft  46 . The secondary sheave  72  is coupled to the right portion of the secondary sheave shaft  62 . 
     The primary sheave  71  includes a fixed sheave half  71   a  positioned outside in the vehicle width direction, and a movable sheave half  71   b  that is positioned inside in the vehicle width direction and faces the fixed sheave half  71   a . The fixed sheave half  71   a  is fixed to the right end of the primary sheave shaft  46   c  and rotates along with the primary sheave shaft  46   c . The movable sheave half  71   b  is disposed on the left side of the fixed sheave half  71   a , and is slidably mounted on the primary sheave shaft  46   c . Thus, the movable sheave half  71   b  rotates along with the primary sheave shaft  46   c , and is slidable in an axial direction of the primary sheave shaft  46   c . A belt groove is formed between the fixed sheave half  71   a  and the movable sheave half  71   b . A cam surface  111  is formed on the left side of the movable sheave half  71   b , and a cam plate  112  is disposed on the left side of the cam surface  111 . A roller weight  113  is disposed between the cam surface  111  of the movable sheave half  71   b  and the cam plate  112 . 
     The secondary sheave  72  includes a fixed sheave half  72   a  positioned inside in the vehicle width direction, and a movable sheave half  72   b  that is positioned outside in the vehicle width direction and faces the fixed sheave half  72   a . The movable sheave half  72   b  is mounted on a right end portion of the secondary sheave shaft  62 . The movable sheave half  72   b  rotates along with the secondary sheave shaft  62 , and is slidable in the axial direction of the secondary sheave shaft  62 . A compressed coil spring  114  is provided on the right end of the secondary sheave shaft  62 . The movable sheave half  72   b  is urged to the left by the compressed coil spring  114 . An axis of the fixed sheave half  72   a  is a cylindrical sliding collar, and is splined to the secondary sheave shaft  62 . 
     A plurality of fan blades  158  is formed on the right side of the movable sheave half  72   b  of the secondary sheave  72 . Blades  158  guide air from the intake duct  153  to the belt chamber  67 , and transport air in the belt chamber  67  to the outside. In this embodiment, the blades  158  are, in the side view, formed to extend radially outward in a spiral manner from the center of the movable sheave half  72   b.    
     In the CVT  30 , a speed reduction ratio is determined by a magnitude correlation between a force of the roller weight  113  that pushes the movable sheave half  71   b  of the primary sheave  71  to the right and a force of the compressed coil spring  114  that pushes the movable sheave half  72   b  of the secondary sheave  72  to the left. 
     In other words, when the rotational speed of the primary sheave shaft  46   c  increases, the roller weight  113  is subjected to the centrifugal force and moves radially outward, thereby pushing the movable sheave half  71   b  to the right. The movable sheave half  71   b  then moves to the right, and a radius of the belt loop around the primary sheave  71  increases. Subsequently, a radius of the belt loop around the secondary sheave  72  decreases. The movable sheave half  72   b  of the secondary sheave  72  resists against the urging force of the compressed coil spring  114 , and moves rightward. Consequently, while the loop radius of the V-belt  73  around the primary sheave  71  increases, that around the secondary sheave  72  decreases. Thus, the speed reduction ratio becomes smaller. 
     On the other hand, a reduction in the rotational speed of the primary sheave shaft  46   c  decreases the centrifugal force exerted on the roller weight  113 . Accordingly, the roller weight  113  moves radially inward along the cam surface  111  of the movable sheave half  71   b  and the cam plate  112 . Thus, the force of the roller weight  113  that pushes the movable sheave half  71   b  to the right decreases. The urging force of the compressed coil spring  114  relatively exceeds the above force, and moves the movable sheave half  72   b  of the secondary sheave  72  to the left. Accordingly, the movable sheave half  71   b  of the primary sheave  71  also moves to the left. Consequently, while the radius of the belt loop around the primary sheave  71  decreases, that around the secondary sheave  72  increases. Thus, the speed reduction ratio becomes larger. 
     As shown in  FIG. 8 , a bowl-shaped bulge portion  94  that bulges (expands) outward (to the right) in the vehicle width direction is formed in the tip side of the secondary sheave shaft  62  in the outer case  53   b . As shown in  FIG. 2 , a connecting pipe  152  is formed obliquely upward to the rear of the bulge portion  94 . Connecting pipe  152  is integrated with the outer case  53   b . The air chamber  154  is connected to the connecting pipe  152  via the intake duct  153 . Here, no limitation is imposed on the connecting mode between the connecting pipe  152  and the intake duct  153 . As shown in  FIG. 8 , in this embodiment, the connecting pipe  152  and the intake duct  153  are fixed by a band  135 . 
     As shown in  FIG. 8 , the right end of the connecting pipe  152  is substantially aligned with the right end of the bulge portion  94  in the vehicle width direction. In addition, as shown in  FIG. 3 , the right end of the air chamber  154  is substantially aligned with the right end of the bulge portion  94  of the transmission case  53 . Thus, the connecting pipe  152 , the intake duct  153 , and the air chamber  154  do not protrude to the outside (right side) of the bulge portion  94 . In other words, the intake duct  153  and the air chamber  154  do not protrude to the outside of the transmission case  53 . Therefore, despite the fact that the intake duct  153  and the air chamber  154  are provided, the maximum width of the motorcycle  10  is not substantially increased, and the vehicle is downsized in the vehicle width direction. 
     As shown in  FIG. 8 , a sealing groove  68   a  is formed on the left side of the periphery of the inner case  53   a . The right-hand periphery of the second case block  35   b  is received in the sealing groove  68   a . An O-ring  68  is inserted in the sealing groove  68   a  between the inner case  53   a  and the second case block  35   b . In addition, a sealing groove  69   a  is formed on the right side of the periphery of the inner case  53   a.  The periphery of the outer case  53   b  is received in the sealing groove  69   a . An O-ring  69  is inserted in the sealing groove  69   a  between the inner case  53   a  and the outer case  53   b . The outer case  53   b  and the second case block  35   b  are fastened by a bolt  70  while holding the inner case  53   a  therebetween. 
     As shown in  FIG. 10 , a front half  121  of the inner casing  53   a  is formed in a bowl shape that bulges leftward. A rear half  122  of the inner casing  53   a  is formed in a bowl shape that bulges rightward. The front half  121  is formed with a hole  121   a  through which the primary sheave shaft  46   c  of the CVT  30  passes. The rear half  122  is formed with a hole  122   a  through which the secondary sheave shaft  62  of the CVT  30  passes. Here, the clutch cover  60  (see  FIG. 8 ) that is interposed between the inner case  53   a  and the second case block  35   b  is omitted in  FIG. 10 . 
     A vent hole  123  is provided in the inner case  53   a . In this embodiment, the three circular vent holes  123  are formed above the vertical center of the inner case  53   a . However, the shape of the vent hole  123  is not limited in any way. In addition, the position of the vent hole  123  is not necessarily limited in an upper portion of the inner case  53   a . In the embodiment, the vent holes  123  are provided both in the front half  121  and in the rear half  122  of the inner case  53   a . However, the vent holes  123  may only be provided in either the front half  121  or the rear half  122 . Furthermore, the number of the vent holes  123  is not particularly limited. 
     A plurality of vent holes  124  is formed in a right lower portion of the second case block  35   b . More specifically, the second case block  35   b  includes a periphery  125  that is arranged rightward in a standing manner. The periphery  125  has a shape corresponding to the contour of the transmission case  53 . The lower side of the periphery  125  is formed into partially-notched slits, that is, of a so-called comb shape. Accordingly, a space  126  defined by the second case block  35   b  and the inner case  53   a  is in communication with the outside of the engine unit  28  through the vent holes  124 . The right side of the rear half of the second case block  35   b  is blocked by the clutch cover  60 . Therefore, the space  126  in the rear half of the second case block  35   b  is formed between the clutch cover  60  and the inner case  53   a.    
     Reinforcing ribs  128  are provided on the comb portion of the periphery  125 . An oil pan  127  is provided below the vent holes  124 . 
     With the above constitution, as shown in  FIG. 11 , air in the belt chamber  67  is guided into the space  126  through the vent holes  123  of the inner case  53   a , and then is discharged to the oil pan  127  through the vent holes  124  of the second case block  35   b . As a result, the air is discharged to the outside of the engine unit  28 . 
     As shown in  FIG. 9 , the centrifugal clutch  41  is mounted on the left portion of the secondary sheave shaft  62 . The centrifugal clutch  41  is a wet-type multiplate clutch, and includes a generally cylindrical clutch housing  78  and a clutch boss  77 . The clutch housing  78  is splined to the secondary sheave shaft  62 , and rotates along with the secondary sheave shaft  62 . A plurality of ring-shaped clutch plates  79  is attached to the clutch housing  78 . The clutch plates  79  are aligned at intervals in an axial direction of the secondary sheave shaft  62 . 
     A cylindrical gear  80  is rotatably fitted on the periphery of the left portion of the secondary sheave shaft  62  via a bearing  81 . The clutch boss  77  is disposed radially inward of the clutch plates  79  and radially outward of the gear  80 , and is meshed with the gear  80 . Thus, the gear  80  rotates along with the clutch boss  77 . A plurality of ring-shaped friction plates  82  is mounted radially outward of the clutch boss  77 . Friction plates  82  are aligned at intervals in the axial direction of the secondary sheave shaft  62 . Each of the friction plates  82  is placed between the adjacent clutch plates  79 . 
     A plurality of cam surfaces  83   a  is formed on the left side of the clutch housing  78 . A roller weight  84  is disposed between the cam surfaces  83   a  and the rightmost clutch plate  79  that faces the cam surfaces  83   a.    
     In centrifugal clutch  41 , a clutch-in (engaged) state and a clutch-off (disengaged) state are automatically switched in accordance with the magnitude of the centrifugal force exerted on the roller weight  84   a.    
     More specifically, when the clutch housing  78  rotates at a speed equal to or higher than a given speed, the roller weight  84   a  is moved radially outward by a centrifugal force, thereby pushing the clutch plates  79  to the left. Consequently, the clutch plates  79  and the friction discs  82  are pressed against each other to bring the centrifugal clutch  41  into the clutch-in state where a driving force of the secondary sheave shaft  62  is transmitted to an output shaft  85  via the centrifugal clutch  41 . 
     On the other hand, when the clutch housing  78  rotates below the given speed, the centrifugal force exerted on the roller weight  84   a  decreases, and thus, the roller weight  84   a  moves radially inward. Consequently, the clutch plates  79  and the friction plates  82  are released from each other to bring the centrifugal clutch  41  into the clutch-off state where the driving force of the secondary sheave shaft  62  is not transmitted to the output shaft  85 . In  FIG. 9 , the front side of the centrifugal clutch  41  (the upper side in  FIG. 9 ) shows the clutch-off state while the rear side thereof (the lower side in  FIG. 9 ) shows the clutch-in state. 
     The deceleration mechanism  42  is interposed between the centrifugal clutch  41  and the output shaft  85 . The deceleration mechanism  42  has a speed-change shaft  100  disposed in parallel with the secondary sheave shaft  62  and the output shaft  85 . The speed-change shaft  100  is rotatably supported by the first case block  35   a  via a bearing  101 , and is also supported by the second case block  35   b  via a bearing  102 . A first speed-change gear  103  that meshes with the gear  80  is provided on a right end portion of the speed-change shaft  100 . 
     A second speed-change gear  104  with a smaller radius than the first speed-change gear  103  is provided on a midsection of the speed-change shaft  100 . A third speed-change gear  105  that meshes with the second speed-change gear  104  is formed on the outer periphery of a right end portion of the output shaft  85 . The inner periphery of the right end portion of the output shaft  85  is supported by the left end portion of the secondary sheave  62  via a bearing  106 . Due to the above constitution, the output shaft  85  is rotatably supported by the secondary sheave shaft  62  via the bearing  106 , and is coaxially (linearly) arranged with the secondary sheave shaft  62 . In addition, a midsection of the output shaft  85  is supported by the left end portion of the second case block  35   b  via a bearing  107 . 
     With the constitution described above, the clutch boss  77  and the output shaft  85  are coupled together through the gear  80 , the first speed-change gear  103 , the speed-change shaft  100 , the second speed-change gear  104 , and the third speed-change gear  105 . Thus, the output shaft  85  rotates in accordance with the rotation of the clutch boss  77 . 
     A left end portion of the output shaft  85  passes through the first case block  35   a , and protrudes outward of the crankcase  35 . A drive sprocket  108  is fixed to the left end portion of the output shaft  85 . A chain  109  is wound around the drive sprocket  108 , and serves as a power transmission mechanism to transmit the drive force of the output shaft  85  to the rear wheel  26 . The power transmission mechanism is not limited to the chain  109  but can be a transmission belt, a gear mechanism with a plurality of combined gears, a drive shaft, or other members. 
     A mechanism to supply lubricating oil to the secondary sheave shaft  62  is now described with reference to  FIGS. 5 and 8 . As shown in  FIG. 5 , the oil pan  127  for storing lubricating oil is formed in a bottom portion of the crankcase  35 . 
     Lubricating oil stored in the oil pan  127  is supplied to a connection  45  between the crankshaft  46  and the connecting rod  51  by an oil pump  130  as a lubricating-oil supply mechanism that is disposed on the oil pan  127  in the crankcase  35 . More specifically, lubricating oil drawn by the oil pump  130  is guided to one or more generally-circular oil supply passages  129  in a plan view that open to a left end surface of the crankshaft  46 , and then is supplied to the connection  45  through the oil supply passages  129 . 
     Lubricating oil supplied to the connection  45  is splashed therefrom in association with rotation of the crankshaft  46 . Lubricating oil splashed in association with rotation of the crankshaft  46  is guided to the inside of the centrifugal clutch  41 . 
     Lubricating oil introduced to the inside of the centrifugal clutch  41  is supplied to the secondary sheave shaft  62 . Then, the lubricating oil returns to the oil pan  127  from an oil drain hole  131  that is provided below and slightly at the rear of the second case block  35   b.    
     A starting system of the engine  29  is now described.  FIG. 12  is a partial sectional view of the engine unit  28  that is equipped with a kick starter  300  and an electric starter  240 . A rider of the motorcycle  10  can start the engine  29  by operating the kick starter  300 . 
     The kick starter  300  has a kick pedal  301 . The kick pedal  301  is attached to a kick shaft  302  provided with a gear  304 . Meanwhile, a gear  306  is rotatably provided on a shaft  305 . The gear  304  meshes with the gear  306 . Rotation of the kick shaft  302  is transmitted to the crankshaft  46  via the gear  304  and the like. The position of the kick pedal  301  is not limited to either the right or the left of the motorcycle  10 . In addition, the longitudinal or vertical position of the kick pedal  301  with respect to the crankshaft  46  is not particularly limited. The kick pedal  301  is placed in a position where it can be actuated as described above. 
     The electric starter  240  of the engine unit  28  is attached to the crankcase  35 . Rotation of the electric starter  240  is transmitted to the crankshaft  46  via gears  241 ,  242 ,  243 . With the above constitution, the electric starter  240  is activated by the rider&#39;s operation of a starter switch  140   a , and then the engine  29  starts. 
     A main stand  200  of the motorcycle  10  is now described. As shown in  FIGS. 13 and 14 , which shows the motorcycle  10  with members such as the body cover  10  removed, the main stand  200  is attached to the motorcycle  10 .  FIG. 13  shows an upright state of the main stand  200  where the rear wheel  26  is lifted off a road surface.  FIG. 14  shows a stored state of the main stand  200  where the rear wheel  26  contacts the road surface. The main stand  200  swings in a given range between the upright and stored states. The main stand  200  is mounted to swing about a pivot  200   b . In addition, as shown in  FIG. 15 , a pivot shaft  204  is pivotally supported by the rear arm brackets  24 L,  24 R. The pivot shaft  204  is rotatable about an axis. The actuation of the main stand  200  into the upright or stored state interlocks with the rotation of the pivot shaft  204 . 
     The main stand  200  is provided with a pin  200   a . In addition, the rear arm bracket  24 R is provided with a pin  203 . A coupling plate  202  is attached to the pin  203 . A main stand switch  201  is attached to the body frame  11  (see  FIG. 1 ) via a bracket  201   a . The position where the main stand switch  201  is attached is not particularly limited in the motorcycle  10  and can be anywhere on the body frame  11 . In this embodiment, the bracket  201   a  is provided on a portion of the seat rail  14 R. The main stand switch  201  is connected by a control unit  162 , which is not shown in  FIG. 15 , and a lead wire  201   b . The main stand switch  201  and the coupling plate  202  are connected to each other via a connecting body  206 . The connecting body  206  is not limited to a specific configuration and may be a wire or a rod-shaped member, for example. An elastic body  205  is supported by the pin  200   a  and the coupling plate  202 . As shown in  FIG. 15 , a stored state of the main stand  200  is retained by urging force of the elastic member  205  in a stretching and contracting direction. Although not shown, an upright state of the main stand  200  is retained by the urging force of the elastic member  205  in the stretching and contracting direction. In this embodiment, a coil spring is employed for the elastic body  205 . However, the elastic body  205  can take any configuration as long as it functions to retain the upright and stored states. 
     The main stand switch  201  is actuated when being pulled by the connecting body  206 . In other words, as shown in  FIG. 15 , when the main stand  200  is in the stored state, the connecting body  206  is not pulled downward. At this time, the main stand switch  201  is turned on by an internal mechanism of the main stand switch  201 . In addition, as shown in  FIG. 13 , when the main stand  200  is in the upright state, the main stand switch  201  moves the connecting body  206  downward for a given distance by the configuration of the coupling plate  202  (see  FIG. 15 ). At this time, the main stand switch  201  is brought into an off state where the switch is not actuated. When the main stand switch  201  is in the on state, the main stand switch  201  is in an energized state where a main stand SW signal  174  is detectable. When the main stand switch  201  is in the off state, the main stand switch  201  is in a de-energized state where the main stand SW signal  174  is not detectable. 
     A brake system and the like of the motorcycle  10  is now described.  FIG. 16  is a schematic structural view of a steering handle  4 . The steering handle  4  includes a handlebar  4   d  that is connected to the steering head pipe, a left grip  4   a  positioned at the left end of the handlebar  4   d  and a right grip  4   b  positioned at the right end of the handlebar  4   d . The right grip  4   b  can be rotated about the handlebar  4   d . When the rider rotates the right grip  4   b , a throttle is operated to control a throttle opening of the engine  29 . 
     A brake lever  4   c  is disposed adjacent to the right grip  4   b . A brake lever  4   e  is disposed adjacent to the left grip  4   a . The operation of the brake lever  4   c  or the brake lever  4   e  by the rider activates a brake of the motorcycle  1 . In this embodiment, a front brake  401  is actuated by operation of the brake lever  4   c  and a rear brake  402  is actuated by operation of the brake lever  4   e . However, the front brake  401  may be actuated by operation of the brake lever  4   e , and the rear brake  402  may be actuated by operation of the brake lever  4   c.    
     A switch box  140  is disposed on the left side of the right grip  4   b . A starter switch  140   a  is disposed in the switch box  140 . As will be described later, the control unit  162  receives a starter SW signal by the rider&#39;s operation of the starter switch  140   a . The control unit  162  activates the electric starter  240  based on the starter SW signal. 
     A left handle section including the brake lever  4   e  is now described in detail. As shown in  FIG. 17 , an arm  5  is fixed to the handlebar  4   d . The brake lever  4   e  is attached to the arm  5  by a bolt  6 . The brake lever  4   e  pivots about a position where the bolt  6  is fastened in a direction G or R. The brake lever  4   e  pivots in the direction G or R within a given range. In addition, a cable  7  is attached to the arm  5  via an attachment  7   a . A wire  7   b  runs inside the cable  7 . When the brake lever  4   e  pivots in the direction G, the wire  7   b  in the cable  7  is pulled to actuate the rear brake  402 . 
     The actuation of the rear wheel brake  402  is not limited to wire  7   b . For example, a brake mechanism actuated by hydraulic pressure may be used. In such a case, the motorcycle includes a master cylinder in which liquid is filled and a member such as a tube from which liquid flows to the master cylinder. This is also applicable to actuation of the front wheel brake  401  by hydraulic pressure. In this embodiment, actuation of the front brake  401  is not particularly limited and description of the actuation of the front brake  401  is thus omitted. 
     A hinge lever  8   e  pushes a switch lever  8   d  by the actuation of a pin  9 . First, the rider pulls the brake lever  4   e  in the direction G in  FIG. 17A . The brake lever  4   e  pivots about the bolt  6  in the direction G in  FIG. 17A , and approaches the left grip  4   a . When the brake lever  4   e  pivots in the direction G to a given position, the pin  9  can be actuated. When the brake lever  4   e  is in the range that the pin  9  can be actuated, the rider pushes down the pin  9  as shown in  FIG. 18A . A finger or a hand can be used to push down the pin  9 . When the pin  9  is pushed down, a shaft  9   b  and a flange  9   c  under the pin  9  are pushed out by the brake lever  4   e . When the pin  9  is pushed down until the flange  9   c  is positioned below a support plate  8   a , the rider releases a load that is applied to the brake lever  4   e . The brake lever  4   e  then pivots in the direction R, but does not return to the original position. At this time, the brake lever  4   e  is temporarily fixed in a given position with respect to the left grip  4   a , and the pin  9  is temporarily fixed in a given position where the flange  9   c  abuts on the hinge lever  8   e . The temporary fixation of the pin  9  is cancelled by rotating the brake lever  4   e  in the direction G from the current position where the pin  9  is temporarily fixed. 
       FIG. 18B  shows a position where the brake lever  4   e  and the pin  9  are temporarily fixed. In this position, the flange  9   c  is stuck on the support plate  8   a,  and thus, the pin  9  is temporarily fixed. In addition, the flange  9   c  pushes the hinge lever  8   e  from the right side to the left side of  FIG. 18B . Consequently, a portion of the switch lever  8   d  is buried in a switch case  8   b.    
     With the switch lever  8   d  partially buried in the switch case  8   b , an internal mechanism of the switch case  8   b  actuates a brake lock switch  802   a . As will be described later, the control unit  162  receives a brake lock SW signal based on the actuation of the brake lock switch  802   a . In addition, a brake switch  801   a  is turned on when the brake lever  4   e  is pulled within the given range in the direction G. The brake switch  801   a  is actuated by the internal mechanism of the switch case  8   b . As will be described later, the control unit  162  receives a brake SW signal based on the actuation of the brake switch  801   a . In addition, the control unit  162  receives the brake SW signal by the rider&#39;s operation of the brake lever  4   c . Based on the brake lock SW signal, the control unit  162  controls start-up of the engine  29 , speed regulation of the engine  29 , and inhibition of the operation of the engine  29 . 
     As shown in  FIG. 19 , the motorcycle  10  includes a main power source  161  connected to the control unit  162 . When the rider brings the main power source  161  into an on state (power-on), the control unit  162  is actuated. As described above, the control unit  162  receives a brake SW signal  171   a  from the brake switch  801   a.  The control unit  162  receives a brake SW signal  171   b  based on the operation of the brake lever  4   c . The control unit  162  also receives a brake lock SW signal  172  based on the operation of the brake lever  4   e . In addition, the control unit  162  receives a starter SW signal  173  based on the operation of the starter switch  140   a . The control unit  162  receives a main stand SW signal  174  based on the actuation of the main stand  200 . 
     The control unit  162  activates the electric starter  240  based on the starter SW signal  173 . The engine  29  is started by the activation of the electric starter  240 . The engine  29  can also be started by the kick starter  300 . In this embodiment, the engine  29  is started either by a starter method including the starter switch  140   a  and the electric starter  240  or by the kick starter  300 . However, the engine  29  may be started only by the kick starter  300  or only by the starter method. 
     With the start-up of the engine, rotation of the engine  29  is transmitted to the CVT  30 . Rotation of the engine  29  is further transmitted to the centrifugal clutch  41  by actuation of the CVT  30 . As described above, the centrifugal clutch  41  intermittently transmits the rotation of the engine  29  based on the rotational speed of the secondary sheave shaft  62 . Thus, the centrifugal clutch  41  transmits rotation of the secondary sheave shaft  62  to a power transmission mechanism  40  when the rotational speed of the secondary sheave shaft  62  equals or exceeds a given speed. The rear wheel  26  rotates by actuation of the power transmission mechanism  40 . The motorcycle  10  travels on the basis of rotation of the rear wheel  26 . 
     The configurations of the front brake  401  and the rear brake  402  are not particularly limited. The front brake  401  and the rear brake  402  may be disc brakes including a disc rotor and brake pads. Alternatively, the front brake  401  and the rear brake  402  may be drum brakes including a brake drum. Moreover, the front brake  401  and the rear brake  402  may employ different types of brake systems from each other. There is no limitation imposed on the configurations of the front brake  401  and the rear brake  402  as long as the friction between the road surface and the front wheel  19  and the friction between the road surface and the rear wheel  26  increase when the brakes are actuated during travel of the motorcycle  10 . 
     Rotation of the rear wheel  26  is regulated by the rear brake  402  and rotation of the front wheel  19  is regulated by the front brake  401 . The rear brake  402  does not make contact with the front wheel  19  while the motorcycle  10  is running; however, there is a case that actuation of the rear brake  402  increases the friction between the front wheel  19  and the road surface. Similarly, the front brake  401  does not make contact with the rear wheel  26 ; however, there is a case that actuation of the front brake  401  increases the friction between the rear wheel  26  and the road surface. Thus, the motorcycle  10  can come to rest only by actuation of the rear brake  402 . In addition, the motorcycle  10  can come to rest only by actuation of the front brake  401 . 
     The front brake  401  is actuated on the basis of operation of the brake lever  4   c , and the rear brake  402  is actuated on the basis of operation of the brake lever  4   e . A brake switch  801   b  is actuated on the basis of operation of the brake lever  4   c,  and the brake switch  801   a  is actuated on the basis of operation of the brake lever  4   e . The control unit  162  receives the brake SW signal  171   b  by actuation of the brake switch  801   b . The control unit  162  receives the brake SW signal  171   a  by actuation of the brake switch  801   a . As described above, the brake lock switch  802   a  is actuated on the basis of actuation of the brake lever  4   e . The control unit  162  receives the brake lock SW signal  172  on the basis of actuation of the brake lock switch  802   a . Operation of the brake lever  4   e  and the pin  9  in a brake lock interlock switch  8  brings the rear brake  402  into a continuously actuated state. This can be made possible by the temporary fixation of the brake lever  4   e  in the given position with respect to the left grip  4   a.    
     The control unit  162  executes engine speed regulation control Rs, engine start inhibition control Pr, and engine operation inhibition control Pe with the brake SW signal  171   a , the brake SW signal  171   b , the brake lock SW signal  172 , the starter SW signal  173 , and the main stand SW signal  174 . In the engine speed regulation control Rs, the control unit  162  regulates the speed of the engine  29  based on each of the signals input in the control unit  162 . In the engine start inhibition control Pr, the control unit  162  inhibits the start-up of the engine  29  based on each of the signals input in the control unit  162 . In the engine operation inhibition control Pe, the control unit  162  terminates the operation of the engine  29  based on each of the signals input in the control unit  162 . Engine speed regulation control Rs, engine start inhibition control Pr, and engine operation inhibition control Pe are now described with reference to the drawings. 
       FIG. 20  is a flow chart of the engine speed regulation control Rs, the engine start inhibition control Pr, and the engine operation inhibition control Pe. The main power source  161  is turned on in step SI when the rider operates an ignition switch  150 . The ignition switch  150  is placed on the outer surface of the body cover  21  (see  FIG. 1 ), for example. 
     In step S 2 , the brake lock switch  802   a  is actuated, and it is determined whether or not it is in an on state. The brake lock switch  802   a  may be actuated to be in the on state before the main power source  161  is turned on. Alternatively, the brake lock switch  802   a  may be actuated to be in the on state after step S 1 . If the brake lock switch  802   a  is in the on state, the process goes to step S 3 . If the brake lock switch  802   a  is not in the on state, the process goes to step S 2   a . When the main power source  161  and the brake lock switch  802   a  are both in the on state, a brake lock indicator Lr (not shown) lights up in a meter display  151 . When the main power source  161  is in the on state, but the brake lock switch  802   a  is in an off state, the brake lock indicator Lr (not shown) flashes in the meter display  151 . The meter display  151  is disposed on an upper surface of a front mask  33   a  (see  FIG. 1 ), for example. 
     In step S 2   a , the brake switch  801   a  is actuated, and it is determined whether or not it is in the on state. Alternatively, the brake switch  801   b  is actuated, and is determined whether or not it is in the on state. If the brake switch  801   a  or  801   b  is in the on state, the process goes to step S 3 . If neither the brake switch  801   a  nor  801   b  is in the on state, the process goes to step S 2   b . If the brake switch  801   a  is actuated to be in the on state in step S 2   a , the control unit  162  receives the brake SW signal  171   a . Or, if the brake switch  801   b  is actuated to be in the on state, the control unit  162  receives the brake SW signal  171   b . Alternatively, if the brake switches  801   a  and  801   b  are both actuated to be in the on state, the control unit  162  receives the brake SW signals  171   a  and  171   b . When the brake switch  801   a  or  801   b  is in the on state, the engine  29  can be started. 
     In step S 2   b , the rider operates the brake lever  4   e  or  4   c . The brake switch  801   a  is actuated to be in the on state by the operation of the brake lever  4   e . The brake switch  801   b  is actuated to be in the on state by the operation of the brake lever  4   c . At this time, the brake lock indicator Lr flashes in the meter display  151 . When the brake switch  801   a  or  801   b  is brought into the on state, the engine  29  can be started. 
     In step S 2   c , the rider operates the brake lock interlock switch  8 . The brake lock switch  802   a  is actuated to be in the on state by the operation of the brake lock interlock switch  8 . At this time, the brake lock indicator Lr is shifted from a flashing state to a lighting state in the meter display  151 . 
     When the brake lock switch  802   a  is actuated, the brake switch  801   a  is also actuated by the structure of the brake lock interlocking switch  8 . Thus, when the brake lock switch  802   a  is in the on state, the brake switch  801   a  is also in the on state. However, as shown in  FIG. 19 , the brake SW signal  171   a  differs from the brake lock SW signal  172 . 
     In step S 3 , the rider starts the engine  29 . As described above, in this embodiment, the engine  29  can be started with the starter switch  140   a  and the electric starter  240 . Alternatively, the engine  29  can be started with the kick starter  300 . 
     A method to start the engine  29  with the starter switch  140   a  and the electric starter  240  is now described. Upon operation of the starter switch  140   a , the control unit  162  activates the electric starter  240 . However, if the rider tries to start the engine  29  while the brake lock switch  802   a  is not in the on state, the engine  29  does not start due to the engine start inhibition control Pr. As shown in  FIG. 19 , as the actuation of the motorcycle  10  at this time, the control unit  162  executes engine start inhibition control Pr 1  that inhibits the activation of the starter motor  240  even with the operation of the starter switch  140   a . Therefore, the engine  29  cannot be started. Alternatively, the control unit  162  executes engine start inhibition control Pr 2  that inhibits the spark plug  55  (see  FIG. 8 ) included in the ignition device  550  of the engine  29  from producing a spark. Therefore, the engine  29  cannot be started. Or, the control unit  162  executes engine start inhibition control Pr 3  that inhibits the fuel supply device  20   a  from supplying fuel to the engine  29 . Therefore, the engine  29  cannot be started. The fuel supply device  20   a  includes a passage for air, which is required for fuel combustion in the engine  29 , and for fuel for the engine  29 . 
     The engine start inhibition control Pr 2  that inhibits the spark plug  55  from producing a spark is also effective in a case where the engine  29  is started with the kick starter  300 . In such a case, even if the crankshaft  46  (see  FIG. 8 ) is forcibly rotated by the kick starter  300  from the outside, the spark plug  55  does not produce a spark. Therefore, the engine  29  cannot be started. In addition, the engine start inhibition control Pr 3  that inhibits fuel supply to the engine  29  is also effective in a case where the engine  29  is started with the kick starter  300 . In such a case, even if the crankshaft  46  (see  FIG. 8 ) of the engine  29  is forcibly rotated by the kick starter  300  from the outside, fuel is not delivered to the engine  29 . Therefore, the engine  29  cannot be started. 
     The process goes to the engine operation inhibition control Pe after the engine  29  is started. In step S 4 , it is determined whether or not the main stand  200  is not in the upright state and the main stand switch  201  is in an on state. As described above, when the main stand  200  is in the upright state, the main stand switch  201  is in an off state. On the other hand, when the main stand  200  is in the stored state, the main stand switch  201  is in the on state. When the main stand  200  is not in the upright state, and the main stand switch  201  is on, the process goes to step S 6 . When the main stand  200  is in the upright state, and the main stand switch  201  is off, the process goes to step S 5   a . If the main stand  200  is in the upright state in step S 4 , the main stand  200  may be used to be in the upright state until the process reaches step S 4 . For example, the main stand  200  may be brought into the upright state before the main power source  161  is turned on in step S 1 . The main stand  200  may be brought into the upright state before the engine  29  is started in step S 3 . 
     In step S 5   a , it is determined whether or not the brake lock switch  802   a  is in the on state if the main stand  200  is determined to be in the upright state in step S 4 . If the brake lock switch  802   a  is in the off state in step S 5   a , the process goes to step S 5   b . If the brake lock switch  802   a  is in the on state in step S 5   a , the process goes to step S 5   c.    
     In step S 5   b , the engine  29  started in step S 3  comes to rest. In other words, operation of the engine  29  is inhibited when the main stand  200  is in the upright state where the rear wheel  26  is lifted off the road surface, and when the brake lock switch  802   a  is in the off state after the start-up of the engine  29 . Therefore, linkage rotation of the rear wheel  26  when the main stand  200  is in use and thus in the upright state can be prevented. 
     In step S 5   c , the main stand switch  201  is turned on. That is, the main stand  200  is shifted from the upright state to the stored state. The rider stores the main stand  200  on the side of the motorcycle  10  as shown in  FIG. 14  from the upright state in  FIG. 13 . Once the main stand  200  is stored on the side of the motorcycle  10 , the main stand switch  201  is brought into the on state. When the main stand switch  201  is turned on in step S 5   c , the process goes to step S 6 . 
     In step S 6 , if the brake lock switch  802   a  is in the on state, the brake lock switch  802   a  is turned off. This can be achieved when the rider operates the brake lever  4   e  and turns off the brake lock switch  802   a  in the brake lock interlock switch  8 . Once the brake lock switch  802   a  is turned off, the engine speed regulation control Rs is terminated. In other words, if the brake lock switch  802   a  is in the on state while the engine  29  is running, the speed of the engine  29  is regulated. 
     When the brake lock switch  802   a  is turned off after the start-up of the engine  29 , the speed regulation of the engine  29  is cancelled. Once the brake lock switch  802   a  is turned off, the brake lock indicator Lr goes out. This allows the start and travel of the motorcycle  10 . 
     Specific controls of the engine speed regulation control Rs are as follows. The control unit  162  executes the engine speed regulation control Rs 1  to the ignition device  550  of the engine  29  that includes spark plug  55  (see  FIG. 8 ) in order to decrease spark frequency of the spark plug  55 . This regulates the speed of the engine  29 . Alternatively, the control unit  162  executes the engine speed regulation control Rs 2  to the fuel supply device  20   a  in order to suppress fuel supply to the engine  29 . This also regulates the speed of the engine  29 . 
     As described before, when the main stand  200  is in the stored state, the main stand switch  201  is in the on state where the switch is actuated. Meanwhile, when the main stand  200  is in the upright state, the main stand switch  201  is in the off state where the switch is de-actuated. Therefore, in this embodiment, the effect of the engine operation inhibition control Pe will not be undermined even with a failure of the main stand switch  201  due to wiring disconnection. 
     As described above, in this embodiment, the speed of the engine  29  is regulated when the engine  29  is running, and the brake lock switch  802   a  is actuated to be in the on state. In other words, the engine speed regulation control Rs is executed when the brake lock switch  802   a  is actuated to be in the on state while the engine  29  is running. Accordingly, even when the rider tries to accelerate by opening the throttle of the engine  29 , the speed of the engine  29  is not increased for any degree of the throttle opening. Fuel consumption is thereby reduced when the engine  29  is running, and the brake lock switch  802   a  is in the on state. 
     In addition, in this embodiment, the engine start inhibition control Pr can be executed in the motorcycle  10 . The engine  29  is not started in the case where the brake lock switch  802   a  is in the off state after the main power source  161  is turned on. The motorcycle  10  hardly consumes any fuel unless the engine  29  starts running and fuel consumption is thus reduced. 
     In addition, the speed of the engine  29  is also regulated when the main stand  200  is in the upright state. While the motorcycle  10  is traveling, the vehicle speed is adjusted based on the speed of the engine  29 . However, when the main stand  200  is in the upright state, the rear wheel  26  is lifted off the road surface and rotation of the rear wheel  26  by the accelerating operation is not transferred to the road surface. Accordingly, when the main stand  200  is in the upright state, the speed of the engine  29  has no influence on the traveling speed of the motorcycle  10 . Thus, if the rider performs the accelerating operation while the main stand  200  is in the upright state, fuel is wasted. However, in this embodiment, the speed of the engine  29  is regulated when the main stand  200  is in the upright state and fuel consumption is thereby reduced. 
     In this embodiment, the engine speed regulation control Rs can easily be cancelled. When the brake lock switch  802   a  is in the on state, the engine speed regulation control Rs is executed to regulate the speed of the engine  29 . However, when the main stand  200  is in the stored state, and the brake lock switch  802   a  is in the on state, the engine speed regulation control Rs can be cancelled by shifting the brake lock switch  802   a  into the off state. When the main stand  200  is in the upright state, and the brake lock switch  802   a  is in the on state, the main stand switch  201  is first shifted into the off state, and the brake lock switch  802   a  is then shifted into the off state. Then, the engine speed regulation control Rs can be cancelled. As described above, the engine speed regulation control Rs can easily be cancelled such that the motorcycle  10  is able to start off and travel. 
     In this embodiment, the start-up of the engine  29  can be inhibited by executing the engine start inhibition control Pr with the ignition device  500 . Thus, start-up of the engine  29  is easily inhibited. 
     In this embodiment, the start-up of the engine  29  can also be inhibited by executing the engine start inhibition control Pr with the fuel supply device  20   a.  Thus, start-up of the engine  29  is easily inhibited. In addition, the engine speed regulation control Rs is executed by suppressing fuel supply to the engine  29 ; therefore, the fuel consumption can further be reduced. 
     In this embodiment, the control unit  162  receives the brake SW signal  171   b  based on operation of the brake lever  4   c . In addition, the control unit  162  receives the brake lock SW signal  171   a  based on operation of the brake lever  4   e.  Furthermore, the brake lock switch  802   a  is actuated by actuation of the brake lever  4   e  and the brake lock interlock switch  8 . The control unit  162  receives the brake lock SW signal  172  based on actuation of the brake lock switch  802   a . When the brake lock switch  802   a  is actuated, the control unit  162  simultaneously receives the brake lock SW signal  172  and the brake SW signal  171   a . The engine start inhibition control Pr is not executed when either the brake SW signal  171   b  or the brake SW signal  171   a  is input. As described above, the engine speed regulation control Rs and the engine start inhibition control Pr are executed by detecting different signals. Therefore, the engine speed regulation control Rs and the engine start inhibition control Pr can be easily executed. 
     In this embodiment, a switch to regulate the speed of the engine  29  after the start-up of the engine  29  also functions as the brake lock switch  802   a  that retains the rear brake  402  in the actuated state. Accordingly, one switch can lock the rear brake  402  and regulate the speed of the engine  29  simultaneously. Therefore, reduced fuel consumption is realized with a simple operation. In addition, a switch to retain the rear brake  402  in the actuated state also works as a switch to regulate the speed of the engine  29 . Accordingly, the speed of the engine  29  does not increase even when the rear brake  402  is actuated, and brake fade is thus suppressed. 
     The brake lock indicator Lr lights up in the meter display  151  based on actuation of the brake lock switch  802   a . While the main power source  161  is in the on state, the brake lock switch  802   a  is actuated, and the control unit  162  receives the brake lock SW signal  172 , the brake lock indicator Lr can light up. When the main power source  161  is in the on state, and the brake lock switch  802   a  is in the off state, a brake lock indicator Lr flashes. Therefore, a rider can easily visually recognize the brake lock state. Furthermore, by recognizing the brake lock state, the rider operates the brake lock interlock switch  8  for the brake lock when the brake is not locked. Therefore, the brake lock switch  802   a  can reliably be brought into the on state, and thus, the engine speed regulation control Rs can be executed appropriately. 
     In this embodiment, the speed of the engine  29  can be regulated by executing the engine speed regulation control Rs with the ignition device  500 . Thus, the speed of the engine  29  is easily regulated. 
     In this embodiment, the speed of the engine  29  can also be regulated by executing the engine speed regulation control Rs with the fuel supply device  20   a.  Thus, the speed of the engine  29  is easily regulated. In addition, the engine speed regulation control Rs is executed by suppressing the fuel supply to the engine  29 ; therefore, fuel consumption is further reduced. 
     &lt;&lt;Other Modification&gt;&gt; 
     In the above embodiment, the brake lock switch  802   a  functions both as the switch to lock the rear brake  402  and as the switch to regulate the speed of the engine  29 . However, a switch to regulate the speed of the engine  29  is not limited to the brake lock switch  802   a  and another switch can be used. 
     For example, the motorcycle  10  may have an engine speed regulation switch that is operated by the rider. No limitation is imposed on the shape and position of the engine speed regulation switch as long as it can be operated by the rider. The engine speed regulation switch may not necessarily be included in the brake lock interlock switch  8  of the above embodiment. 
     Engine speed regulation control Rs, engine start inhibition control Pr, and engine operation inhibition control Pe can be executed when the engine speed regulation switch is turned on. When the engine speed regulation switch is in an on state, the control unit  162  is brought into an energized state where an EG speed regulation SW signal can be detected. Meanwhile, when the engine speed regulation switch is in an off state, the control unit  162  is brought into a de-energized state where the EG speed regulation SW signal cannot be detected. 
     As in this modification, when the engine speed regulation switch is used, the brake lock switch in  FIG. 20  is replaced by the engine speed regulation switch for the engine speed regulation control Rs, the engine start inhibition control Pr, and the engine operation inhibition control Pe. In addition, the brake lock SW signal  172  is replaced by the EG speed regulation SW signal for the controls shown in  FIG. 20 . However, in this case, the brake switch  801   a  is not always in the on state when the engine speed regulation switch is in the on state. In this case, the on/off state of the brake switch  801   a  is shifted by the operation of the brake lever  4   e.  Furthermore, as described above, the mounting position of the engine speed regulation switch is not particularly limited. However, it is preferably located in the proximity of the steering handle  4  in order to facilitate operation with the brake lever  4   e  or  4   c.    
     Moreover, when the engine speed regulation switch is in the on state, the engine  29  can be started by the kick starter  300 . When the engine speed regulation switch is in the on state, and either the brake switch  801   a  or  801   b  is in the on state, the engine  29  can be started by the electric starter  240 . As described above, start-up methods of the engine  29  can be selected in accordance with the on/off state of the brake switch  801   a  or  801   b  and with the on/off state of the engine speed regulation switch. When the engine speed regulation switch is in the off state, the engine  29  cannot be started by either method. Therefore, when the engine  29  is running, and the engine speed regulation switch is actuated to be in the on state, the speed of the engine  29  is regulated. 
     The present invention is useful for a motorcycle.