Four stroke motors are used to power virtually every car and street motorcycle manufactured today. You may have heard the term "four stroke", but do you know what each cycle (or stroke) does?
1) Intake: In this cycle, air and fuel is drawn into the cylinder through an intake valve as the piston travels downward.
2) Compression: The piston, driven upward by the crankshaft, compresses the air and fuel mixture at the top of the cylinder.
3) Power: A spark ignites the air / fuel mixture and the resulting explosion drives the piston downward. This downward motion moves the crankshaft and creates power.
4) Exhaust: The burned gasses are forced out of the open exhaust valve by the upward motion of the piston, and the cycle starts all over again.