Patent ID: 7032561

Claim:
An engine of a snowmobile in which a front half of a snowmobile body is covered by an engine hood so as to form an engine room therein in which a water-cooled engine is transversely mounted, said engine comprising: a crank case including an upper crank case half and a lower crank case half which are mated together at mating surfaces thereof; a cylinder block disposed above the crank case; a cylinder head disposed above the cylinder block; and a crank shaft rotatably supported at the mating surfaces of the upper and lower crank case halves in a manner inclined rearward, wherein said cylinder head is covered by a head cover so that a mating surface thereof is inclined forward such that a front side of the cylinder head is lower, in level, than a rear side thereof, said cylinder head is formed with a plug hole for inserting an ignition plug and a drain port at the rear side portion thereof, a drain passage is formed so as to extend downward from the plug hole to the drain port, and an exhaust port is branched into two portions between which a cooling water jacket is arranged.