Hey Andy,

A) 4-stroke engine goes through 4 stages

1. Intake: The intake valve is open, and fuel is drawn in with a downward stroke.

2. Compression: As the piston moves upward, the fuel is compressed.

3. Power: After the fuel is compressed, it is ignited to produce the engine’s power.

4. Exhaust: The exhaust valve opens, and the exhaust gases exit the cylinder.

B) 2-stroke engine goes through 2 stages

1. Upstroke (ignition/compression): The piston goes up, air and fuel enter the crankcase. The fuel-air mixture is compressed and ignited.

2. Downstroke (power/exhaust): Once the fuel is ignited, the piston is pushed down, and the exhaust is expelled.

A 4-stroke engine is more fuel-efficient and environmentally-friendly, at the same time, 2-stroke engine requires fewer moving parts for easier maintenance.