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 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.