Yamaha dirt bikes are led by the YZ450F, which is campaigned by James Stewart in the AMA Motocross and Supercross series. The 450 MX machine is complemented by the YZ250F and a slew of 2-stroke YZs - one of the few manufacturers to produce the little smokers. Other Yamaha off-road motorcycles are the WR450 and WR250 enduros, as well as the TT-R line. The TW200 is a fun entry-level dual-sport, with the WR250X a purpose-built supermoto. History of Yamaha Motorcycles