Patent ID: 7104252

Claim:
An oil-in-fuel lubricated four-stroke combustion engine having at least one reciprocating piston disposed in a cylinder and defining in part a combustion chamber, an intake port of the cylinder communicating intermittently by an intake valve and between the combustion chamber and an intake channel, an exhaust port of the cylinder communicating intermittently by an exhaust valve and between the combustion chamber and an exhaust channel, and a mechanical mechanism operably connecting the intake and exhaust valves with the piston and disposed in a generally sealed cavity, the four-stroke combustion engine comprising: a rotary-type carburetor having a mixing passage extending through a carburetor body and communicating with the intake channel, a cylindrical valve chamber intersecting the mixing passage, a rotary throttle member disposed rotatable in the cylindrical valve chamber, a bore extending through the rotary throttle member with generally opposed ends constructed and arranged to adjustably continuously communicate with and rotate generally into alignment with the mixing passage; and a vent passage of the carburetor extending between the sealed cavity and the rotary throttle member for continuous communication of the sealed cavity with the mixing passage by opening directly into the bore through the rotary throttle member between the ends of the bore.