Lesson 1/Learning Event 1
THE TWO-STROKE CYCLE
Another method of engine operation is the two-stroke cycle. It is used mostly in small gasoline engines and
also with some large diesel engines. In this lesson we will only discuss the small gasoline engines, as diesel
engines are covered in another lesson.
FIGURE 15. TWO-STROKE-CYCLE ENGINE.
Construction of the Two-Stroke-Cycle Engine
The two- and four-stroke-cycle engines differ because the two-stroke cycle uses ports in the cylinder wall in lieu
of valves. By using intake and exhaust ports in the cylinder wall, the valves, tappets, camshaft, and timing gears
are not needed.