Four-stroke engines power gasoline and diesel oil vehicles. Two-stroke engines are found in equipment that requires a lower level of power, such as chain saws, model planes and dirt bikes.
In comparison to four-stroke engines, two-stroke engines do not have valves. This characteristic makes them lighter than four-stroke engines. Two-stroke engines fire during each revolution, and four-stroke engines fire every other revolution. A standard four-stroke engine must sit upright to function properly, but a two-stroke engine operates in any position; this characteristic is crucial to power tools' proper functioning. Two-stroke engines also give off a heavy amount of pollution and have a shorter lifespan than four-stroke engines.