How does a two-stroke engine differ from a four-stroke engine?

A two-stroke engine indeed completes a power cycle in just two strokes of the piston, which are one full revolution of the crankshaft. This design allows for a power stroke with every crankshaft revolution, resulting in a more compact engine that can produce power more frequently compared to a four-stroke engine, which requires four strokes (intake, compression, power, and exhaust) to complete one power cycle.

In practical terms, this means that for applications where size and weight are critical, such as in motorcycles or small outboard motors, two-stroke engines can deliver higher power levels relative to their size. They also tend to have a simpler design because they do not require valves; instead, they use ports for intake and exhaust, which can lead to fewer mechanical components.

The power output characteristics can lead to differences in efficiency and emissions, but the primary defining feature remains the number of strokes required to complete the power cycle. This fundamental difference gives two-stroke engines their unique operational characteristics compared to four-stroke engines, and it is why many applications favor them in certain scenarios.