In a two-stroke engine cycle, how many crankshaft revolutions make up a complete cycle?

In a two-stroke engine cycle, how many crankshaft revolutions make up a complete cycle?

• A. Two
• B. Three
• C. Four
• D. One

Answer: (D)

In a two-stroke engine, the complete thermodynamic cycle fits into a single crankshaft revolution because intake, compression, ignition/power, and exhaust are arranged to occur within the same up-and-down motion of the piston. The porting design allows fresh charge to enter and burnt gas to exit while the piston is moving, so the cycle is finished and ready to start again after just one turn of the crankshaft. This is what makes a two-stroke cycle complete in one revolution, unlike a four-stroke engine which needs two revolutions to cover all four events.

In a two-stroke engine, the complete thermodynamic cycle fits into a single crankshaft revolution because intake, compression, ignition/power, and exhaust are arranged to occur within the same up-and-down motion of the piston. The porting design allows fresh charge to enter and burnt gas to exit while the piston is moving, so the cycle is finished and ready to start again after just one turn of the crankshaft. This is what makes a two-stroke cycle complete in one revolution, unlike a four-stroke engine which needs two revolutions to cover all four events.