Motorcycle engine cam chest having reed valve assembly

摘要

A motorcycle engine includes a crankcase, a cam chest, and a separating wall between the crankcase and cam chest. An opening is defined in the wall and communicates between the cam chest and crankcase. A valve assembly, which is preferably a reed valve assembly, covers the opening and permits one-way flow of air from the crankcase into the cam chest in response to pressure differentials caused by reciprocation of the engine's pistons. The air is then forced into the engine's rocker boxes through the engine's pushrod tubes and forces oil in the rocker boxes to return to the crankcase through narrow oil drainback passages.