1. Composition of gasoline engine Gasoline saws generally use crankcase preloaded scavenging two-stroke machines, which are all cylinder air-cooled. According to the function, the gasoline engine is composed of four systems: mechanical, electrical, fuel supply, and airflow. 1) The mechanical system includes cylinder, piston group, connecting rod, crankshaft, box, etc. The function is to achieve gas sealing, withstand gas pressure and mechanical force, and ensure a certain movement relationship. &