chain saws have carburetors, that mix fuel and air, The air-fuel mixture passes into a cylinder, which works much like the ones in a car engine but with only a simple push-pull (two-stroke) action instead of the more complex (four-stroke) cycle used in a car. Inside the cylinder, the air-fuel mix is ignited by a spark (sparking) plug, burns, releases its energy, and pushes a piston back and forth.