In the two stroke engine, all four events are integrated into one simple downward stroke, and one upward stroke. Two strokes. Intake and exhaust are both integrated into the compression and combustion movement of the piston, eliminating the need for valves. This is accomplished by an inlet and exhaust port in the wall of the combustion chamber itself. As the piston travels downward from combustion, the exhaust port is exposed allowing the spent gasses to rush out of the chamber.
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