We rode the WR in a closed-course competition setting, unlike how it is sold off the floor at the Yamaha dealer. For more information on this setup, check out www.dirtrider.com, as you may be a little disappointed if you buy a WR and try to ride it box-stock. There are a few things, such as the throttle stop, the muffler insert and the secondary ignition curve, that keep the bike really choked up and, along with the sized-down airbox opening and complementary leaner jetting that amplify the effect, aim at passing the drive-by sound test and emissions requirements. Even an air-injection system is mounted on the side of the WR engine to burn off excessive emissions. The AIS system in particular is now being looked for by authorities where emission-compliant vehicles are mandatory (during the summer in California, don't ask!).
The starter isn't the fastest spinning, but the bike fires right up. It then takes a bit longer to warm than a YZ. In Costa Rica (where the bike was unveiled before the media) every tank of gas was a new surprise-the quality was random, making it hard to truly feel how the bike was running-but these WRs proved they could and would run on low-octane fuel. They hiccuped and detonated, but they survived. We waited till we got a test bike back to California, where we could put some hard miles on it, to see what the new motor was really made of. Plainly put, it rips. It is much more lively than the old WR but at the same time still stays very smooth and progressive in the power buildup. The jetting we finally settled on is in the included chart. And if it is ever finicky, especially at idle or low throttle positions, just play with the fuel screw. The best thing about the bike is the big power that still comes with such a quiet exhaust note. With only the smallest muffler end-tip insert removed, the bike is whisper quiet and never has that snap-crack-burst of sound nor really roars decibels, even in the upper Rs. The bike is very quick and the power delivery is great for low-traction situations; it grabs traction when there is very little available. We have nothing but praise for this motor.
The handling isn't as light and flickable feeling as the new WR250F. But when compared with last year's steel-framed bikes, the 450 definitely has a lighter feel that is most notable in side-to-side movements with the bike and again in the steering feel through the bar. It still has some girth to it, a good weight that helps the bike stay planted and makes it stick to the ground rather than deflect and dance over things, though some of its bite is from the power. It isn't heavy feeling by any means; it's definitely lost some hulk compared with the last couple of years of WR450Fs. You will notice this. Kiss top-heavy feel good-bye and good riddance!