Monolithic block and valve train for a four-stroke engine

摘要

A cylinder crankcase for a four-stroke engine Is disclosed. The cylinder crankcase includes a cylinder head, cylinder block, and crankcase which are monolithic. A half-crank crankshaft bears in a crank arm, which is included In the crankcase. The 5 cylinder crankcase Includes a belt driven valve train and crank arm that Includes a pocket containing a crank gear attached to the crankshaft for driving the belt. & R0