Yamaha WR450F

The Yamaha WR450F is an off-road motorcycle made by Yamaha Motor Company, with a liquid-cooled single-cylinder engine of 450 cc. First offered in 1998 as the 400 cc WR400F, it shared many parts and ideas with the YZ400F motocross model and helped usher in the four-stroke era that ended the dominance of two-stroke engines in motocross and off-road racing. The WR in the name marks a wide-ratio gearbox, in contrast to the close-ratio gearbox of a motocross racer. The displacement rose to 426 cc in 2001 and to 449 cc in 2003, when an electric starter became standard; an aluminum frame came in 2007, fuel injection and a new chassis in 2012, and the reverse-slant four-valve engine of the YZ450F in 2016. A rare 2-Trac version sent up to 15 percent of the power to the front wheel by an oil pump and was used in enduro racing.