OMC VHS: Inside The Two-Stroke Engine

A two-stroke engine completes one power cycle with only two piston strokes by performing multiple functions simultaneously: while the piston compresses the air-fuel mixture in the cylinder, it simultaneously draws fresh mixture into the crankcase, and while the cylinder mixture is ignited to produce power, it simultaneously compresses the crankcase mixture to prepare for the next intake. This design is simpler than four-stroke engines but less fuel-efficient due to scavenging losses where fresh fuel can escape through exhaust ports. The choice between two-stroke and four-stroke engines depends on application requirements including power needs, weight constraints, fuel economy, and operating conditions.