In its sophomore year as an aluminum-framed motocross bike, the 2007 Yamaha YZ250F is motivated to return to a dominating role in the world of professional racing. In fact, Yamaha will have two of these bikes in full-factory trim on its race squad this year. And with young speedsters Broc Hepler and Josh Hill at the controls, it's safe to say the blue team expects to step on a lot of podiums. But how new is the new blue?
Yamaha modified a fair amount of components from the '06 model with serious goals set on enhancing the lightweight feel and overall handling precision of the little YZ-F. And this is the area where most of the improvements were noticed in our first weeks of testing. Yamaha claims the bike is three pounds lighter this year; our scales tell us it's more like five. But the feel of that weight loss is more noticeable on the track than in the garage. The bike seems greatly balanced with a solid, in-touch feel with the ground. Changing lines or diving inside at the last minute is effortless, and the bike feels sweet in the air, too. While the blue team went to weight-saving extremes (like swapping 12mm for 10mm bolt heads in the subframe/rear end and shrinking the front axle carrier, brake-caliper mount assembly and a host of other hardware), we think their weight placement, particularly the fine-tuning to engine location and orientation in the chassis, is what really makes the bike feel light but not jittery or busy.
The '06 front-end issues aren't as noticeable, either-almost eliminating our only real handling complaint from last year. No doubt this is directly related to the head tube being pushed back 3mm-putting some weight on the front and thus tightening the turning. Out back, the shock is lengthened 1.5mm as well, further tightening the chassis. Also, this bike really stays straight in the rough stuff and big whoops at any speed. Basically, Yamaha is ruling the lightweight feel with its new thumpers and working right through the alloy-framed growing pains quickly.
A new, longer muffler end-cap with a smaller diameter and more-angled exit hole, which quiets the usually raspy motor, and the bike's new gearing (a 49-tooth rear sprocket) seem to be the biggest propulsion changes to the bike. Even though the routine ignition-map changes and carburetor adjustments adorn the new Yamaha, the motor seems very similar to last year's in character. In delivery, it's a bit different. The extra tooth pulls the bike out of the bottom a little better, but then the bike sort of softens up on top. Neither end of the power spectrum is as impressive as the solid midrange. In reality, this YZ-F feels softer down low and signs off more than the '06er. Does this bother us? Yes and no. Yes, we can deal with some bottom-end mellowness, especially when traction is an issue. And It's easy to carry more revs into low-speed stuff to ensure a speedy exit. But on top, where 250Fs are used to bouncing around near the rev-limiter, this motor's attitude has us shifting more often in search of the juicy power.
It's refreshing to see Yamaha tuning its aluminum chassis so effectively in such a short time. And it's very nice to see the tuning-fork guys are not gambling with wild, potentially unreliable motor overhauls. This bike has been great for a long time. With a proven durability record and a manufacturer's warranty, it's still really easy to choose blue. However, our 250F shootout will uncover if the YZ-F can still run with some of the traditionally power-strong models and some impressive newcomers to the class.