2-Stroke engines are the most zippy machines in the motorcycle business. The 2-stroke engines are manly made for competitive racing. I am not quite up to date with the details but I know it has somthing to do with something stroking twice before one cycle where the four stroke engine strokes four times before one cycle. With the two stroke engines you must mix the oil with the gasoline. The government just composed a law restricting two stroke engines and you must have a spark arrestor and you may only ride them during the fall, winter, and spring.