A type of internal combustion engine; a two-stroke engine has its name because it completes a power cycle of two strokes or two up and down movements of the piston during one crankshaft revolution. A four-stroke engine requires four up and down movements (or strokes) of the piston to complete its cycle. Bike engines either have two or four strokes. Two-stroke (or 2-stroke) engines offer more torque and use a gas/oil mixture, they are known to be noisier and emit more exhaust. A four-stroke or 4-stroke engine on the other hand provides a much smoother ride with less exhaust. They also only take gas in the tank.