Yamaha, the Japanese motorcycle manufacturer, made major changes to its WR off-road bikes in 2007. The 250F and 450F got new aluminum frames, a reworked suspension, and a new engine design with a built-in sump and enclosed oil passages. Those changes were carried over for the 2008 production year—and Yamaha added a pair of dual-purpose bikes to the WR line, the 250R and 250X.
Both the 250F and 450F are powered by liquid-cooled, single-cylinder four-stroke engines. The 250F’s engine has a 249cc displacement; the 450F displaces 449cc. Both have dual overhead cams with Yamaha’s classic five-valve configuration and Keihin carburetors. The five-speed manual transmissions on both models are chain-driven.
The two new models are intended for street use as well as trail riding. Both models use a liquid-cooled, 250cc, single-cylinder four-stroke engine, but unlike the F models, these two have a new, four-valve cylinder head and fuel injectors. They also have six-speed manual transmissions rather than five-speed transmissions.
All four bikes have Kabaya inverted forks in front, with adjustable preload and rebound damping, and twin-sided swing arms in the rear, with adjustable spring preload and rebound damping. Three models—the 250F, 250R, and 450F—have 9.8-inch hydraulic disc brakes in front, and not much smaller discs in back. The 250X is designed to shine on the supermoto track, and in keeping with that purpose, it has a larger brake rotor in front and smaller wheels than its counterpart.
These bikes are suitable for a wide range of skill levels in their riders, powerful enough to climb hills and, for the two street-legal models, handle freeway speeds.