In a 4-cycle small gas engine, how many complete revolutions must the crankshaft make to complete one cycle?

In a 4-cycle small gas engine, the crankshaft must complete two full revolutions to execute one complete cycle of intake, compression, power, and exhaust strokes. Each cycle consists of these four distinct phases, each requiring different movements of the engine components.

During the first revolution of the crankshaft, the intake and compression strokes occur. The intake stroke pulls in the air-fuel mixture while the compression stroke compresses this mixture in the cylinder. Upon completing the first revolution, the second begins with the power stroke, where the compressed mixture is ignited and expands to push the piston down. Finally, the exhaust stroke occurs, expelling the spent gases from the cylinder.

Thus, because two complete revolutions of the crankshaft are required to complete all four strokes, this is the correct answer for the number of revolutions needed for one cycle in a 4-cycle engine.