A two-stroke engine, is one of two main types. The other being a four-stroke. The two-stroke is named so because it does the same four processes of a four-stroke(intake, compression, power, exhaust) in two strokes of a piston instead of four. Two-stroke engines make a noise that sound somewhat like a swarm of bees. For years they were used far more then four-strokes in all motocross and Supercross racing. In recent years, though, the AMA has allowed for larger engine sizes for four-strokes, and so two-strokes have diminished in popularity.
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