Patent ID: 7017532

Claim:
An engine for a personal watercraft, comprising: an open-looped cooling system configured to take in water from outside the watercraft, for use as cooling water to cool the engine and thereafter discharge the cooling water outside the watercraft; a cylinder block having a water jacket formed inside thereof, the water jacket being coupled to the open looped cooling system such that the cooling water flows through the water jacket; a cylinder head connected to an upper end face of the cylinder block so as to form a combustion chamber; and a piston that reciprocates within cylinder block; wherein the water jacket is provided in an uppermost end portion of the cylinder block so as to surround the piston, the water jacket being formed so as to open into the upper end face of the cylinder block facing the cylinder head; and wherein the water jacket extends downward from the upper end face of the cylinder block, and a dimension of the water jacket from the upper end face of the cylinder block to a lowermost portion of the water jacket in a reciprocation direction of the piston is equal to or less than a half of a reciprocation distance of the piston so that excess cooling of the cylinder block is inhibited.