Motorcycle Engine

A motorcycle engine comprises an oil pump and a cam chest cover. The cam chest cover comprises a crankshaft pinion bearing and a camshaft bearing. The engine is configured and adapted such that the oil pump supplies pressurized oil to the crankshaft pinion bearing and the camshaft bearing. The engine is also adapted to receive both a crankshaft position sensor and, alternatively, a camshaft position sensor. The cam chest cover also comprises a pressure relief valve that diverts excess oil into a scavenge oil passageway that leads out of the engine. Still further, the engine comprises at least one check valve that allows air to pass from the wheel chest to the cam chest, but not the reverse.