What is the fourstroke combustion cycle? | HowStuffWorks
The four strokes in the Otto cycle are the intake stroke, the compression stoke, the combustion stroke and the exhaust stroke. As the crankshaft revolves, it moves the piston down, and the intake valve opens to let in a mixture of air and fuel (this is the intake stroke). When the piston moves back up, it compresses the air/fuel mixture (compression stroke), so when the spark plug releases a ...