The Yamaha YZ is a line of two-stroke and four-stroke off-road motorcycles made by Yamaha Motor Company. They are designed for motocross racing and have been made since the early 1970s. Yamaha YZ models include the YZ125, YZ250, YZ250F, YZ450F, YZ250X, YZ450FX, YZ250FX, YZ125X, YZ250XF and YZ450XF.