Abstract: An engine for a planing-type boat can have a water jacket, which is provided in a main body of the engine and which is supplied with cooling water for cooling the engine. The water jacket can include a ceiling with its rearward portion higher than its forward portion. The water jacket can also include a water drain provided at the rear highest portion of the ceiling to discharge cooling water out of the water jacket. In addition, a head bolt fastening portion for receiving a bolt is provided on an outer side portion of the water jacket in the cylinder head, and a rib is provided in a portion of the water jacket that corresponds to the head bolt fastening portion.

Abstract: An engine for a planing-type boat can have a water jacket, which is provided in a main body of the engine and which is supplied with cooling water for cooling the engine. The water jacket can include a ceiling with its rearward portion higher than its forward portion. The water jacket can also include a water drain provided at the rear highest portion of the ceiling to discharge cooling water out of the water jacket. In addition, a head bolt fastening portion for receiving a bolt is provided on an outer side portion of the water jacket in the cylinder head, and a rib is provided in a portion of the water jacket that corresponds to the head bold fastening portion.

Abstract: A lubrication system for an internal combustion engine includes an oil pump assembly driven by the crankshaft. The oil pump can be mounted in various positions for maintaining a low center of gravity of the engine. Optionally, or in addition, the engine can include a bearing disposed between a valvetrain drive gear and an output drive gear.

Abstract: A personal watercraft features a four-cycle engine. The four-cycle engine has an intake valve and an exhaust valve. The intake valve and the exhaust valve are controlled through a use of a cam drive arrangement. The cam drive arrangement is contained within a protective housing. A number of waterjackets are provided to the housing to control the temperature within the housing. In addition, the watercraft features a protective housing in which a starter motor is mounted to the cylinder block. The housing features two members that can be mounted to the cylinder block together while one member can be removed for access to the starter motor.

Abstract: A lubrication system for an internal combustion engine includes an oil pump assembly driven by the crankshaft. The oil pump can be mounted in various positions for maintaining a low center of gravity of the engine. Optionally, or in addition, the engine can include a bearing disposed between a valvetrain drive gear and an output drive gear.