Just getting around to reading the December '07 Dirt Bike magazine. In there, they have a brief writeup on the WR-250R and WR-250X.
Every 20 years or so the Japanese motorcycle industry rediscovers the dual-sport market. Now it's Yamaha's turn. The WR250R is the most high-tech machine Yamaha has ever made for on/off-road use. It has an aluminum frame, electronic fuel injection, liquid-cooling and double overhead cams. That's quite a leap forward from the TW200.
Still, the new WR isn't in the same league as the all-dirt WR250F, performance wise. The motor is based on an existing Japanese domestic model and gets a pentroof four-valve head rather than Yamaha's five-valve design. The frame has some bolt-together members. Still, the electronic fuel injection is nothing to sneeze at, as Yamaha is probably planning to incorporate EFI on its motocross bikes by 2009. Another high-tech feature not seen on the production motocross bike is EXUP, a variable exhaust system used on some street bikes and occasionally seen on the works MX bikes. The price for the new WR250R will be $5899. Yamaha will also release a Supermoto version (see page 120) for $5999.