1. Intake stroke
The piston moves down in the cylinder, creating a vacuum that draws air-fuel mixture into the chamber through the intake valve. The intake valve closes once the piston reaches the bottom of the stroke.
2. Compression stroke
With both the intake and exhaust valves closed, the piston moves up in the cylinder, compressing the air-fuel mixture. This increases its pressure and temperature, making it more combustible.
3. Power stroke
The spark plug ignites the compressed air-fuel mixture, creating a controlled explosion that drives the piston down the cylinder. This generates power that is transmitted to the crankshaft.
4. Exhaust stroke
The exhaust valve opens as the piston moves up the cylinder, expelling the burnt gases from the combustion chamber. The piston continues to move up, pushing the burnt gases out of the exhaust port. The exhaust valve closes once the piston reaches the top of the stroke, and the cycle begins again with the intake stroke.
