Two-stroke motorcycles are powered by a two-stroke engine, which completes a power cycle in just two strokes of the piston. This design allows for a simpler engine structure, often resulting in lighter weight and higher power-to-weight ratios compared to four-stroke engines. They are commonly used in dirt bikes and smaller motorcycles due to their ability to deliver quick acceleration and high RPMs. These motorcycles mix oil with fuel for lubrication, which can lead to higher emissions and increased fuel consumption. Despite these drawbacks, two-stroke motorcycles are favored in certain racing and off-road applications for their responsiveness and ease of maintenance.