Two-Cycle Engine

an internal combustion engine in which the work cycle is completed during one revolution of the crankshaft. The cycle includes intake of the fuel mixture (or air), compression, and combustion, as well as expansion and exhaust of gases; the whole cycle is completed during two strokes of the piston.

A part of the fresh charge entering the cylinder is invariably lost through the exhaust openings during the scavenging part of the cycle. This loss lowers the economic efficiency of the two-cycle engine. This type of engine also has the disadvantage of a high thermal loading of the piston, tending to lower the reliability of the engine. A complicated exhaust-scavenging arrangement is an additional disadvantage.