Yamaha hopes to jump in front of its Lites class competitors this year. After changing to the aluminum chassis last year, Yamaha has stuck with it and improved the handling characteristics.
Yamaha enters the 2007 season in search of better performance from the YZ250F and subsequent victories in shootouts and Lites class competition. Rather than throwing a boatload of major changes at an already solid 2006 package, Yamaha took a deliberate, calculated approach towards fine-tuning and improving the weaknesses which surfaced last year.
We got to try out two brand-new moto offerings recently as Yamaha
rolled out the blue carpet on its 2007 YZ250F at the yet-to-be-opened Milestone MX Park in Riverside, CA. As stoked as we were to be invited to an all-new facility that boasts five different tracks, we were more excited about the reworked YZ-F.
Yamaha had three goals in mind when it went to the drawing board for the '07 250F: improved engine performance, better handling and reduced weight. Hearing this during our technical briefing was enough to perk up my caffeine-deprived senses because it sounded like a good recipe for spicing up Yamaha's popular middle-weight machine.
Last year the YZ250F was a solid overall package. Unfortunately, that in itself was its ultimate demise due to the fact that nothing about the bike stood out enough to make us fall in love with it. Even though it was completely competent and had an all-new aluminum chassis, the major gripe was that the motor simply didn't have enough juice compared to the rest of the Lites contenders and it offered little in the way of personality.
The rear Kayaba shock has been lengthened 1.5mm, similar to the 2006 YZ450F. The change is one of several that combine to increase cornering ability by sharpening the steering characteristics.
That lightweight chassis was something we liked in '06 and it's back again in 2007 with some noticeable improvements. Yamaha still refuses to join the beefy twin-spar trend that has swept the rest of Japan but that isn't a bad thing. The Blue engineering team proved that you can still build a light, nimble and predictable aluminum chassis without succumbing to industry peer pressure. Notable differences this year are in the steering head which has been moved 3mm farther back and the new engine mounts that force the motor into a more upright position. Yamaha pulled the magic rotating cylinder head trick on the last year's YZ450F
and found enough benefits from the mass centralization to transfer it to the smaller model.
Moving the steering head rearward places more weight on the front wheel, thus increasing feel and control of the front end. Wheelbase on the YZ-F is now shortened 0.6 inch to 57.9 inches with the frame modification and a 49-tooth rear sprocket which brings the rear wheel forward compared to the 48T on the '06. Add that to the tightest Japanese rake of 27.0 degrees and 4.6 inches of trail and accentuated weight on the front wheel provides sharp, steady turning. One of the things we liked so much about last year's YZ250F was its planted feeling, and the new bike retains that unshakable nature.
Big Blue added to the grip-seeking pressure on the front end by raising the rear. The Kayaba shock is 1.5mm longer to direct the rider and the bike forward. The spring is still titanium but the rate has changed from 5.1kg to 4.9kg. I set the sag to 102mm and the rear end tracked as straight and true as I remember it.
The added pressure on the front end and lighter steering makes the YZ250F much easier to blast corners with. Our sandy test track wasn't the best for getting a feel for the front end but the improvements were still large enough to be easily felt.
The 48mm Kayaba fork was also its predictable, forgiving self. The outer tubes were strategically thinned between the two triple clamps for what Yamaha claims is a 4% reduction in stiffness. Whether or not the engineers were able to build in this extra flex for a more forgiving feel was lost on me in the Glamis-like sand at the Milestone track. It'll take some rough braking bumps for a good demonstration, but our testing facility was without. Overall the suspension felt very accommodating - exactly what I expected since the components are virtually unchanged from the stellar 2006 model
Yamaha slapped on a new Pro Taper handlebar that is 8mm taller than last year's version. This easy mod lands on the plus side by opening the rider compartment. I found it easy to move around on the '06 250F, and this new control system is extra roomy and also compensates for the shortened frame.
What happened below the handlebars also played a part in lightening the steering and lowering overall weight, both of which add to the improved handling. The bottom triple clamp is now forged rather than cast aluminum and has been shaved down to further increase weight savings. Even the smallest things have been addressed, such as the fork's pinch bolts dropping from 40mm in length to 35mm and the handlebar mounts have a 2mm-slimmer shaft. Speaking of bolts, there are 25 new, lightweight 10mms used on the subframe, seat and exhaust that take the place of former 12 millis. Truth be told, you probably won't notice the miniscule weight savings, but you'll surely appreciate more efficient wrenching and less tool swapping during shop time - definitely a nice touch.
This front brake rotor looks like it was stolen off Kawasaki's KX250F, but the real news is the shrunken forged caliper. Smaller pistons and pads grip the new rotor, but unfortunately we weren't satisfied with our evaluation of the new setup. From what we could tell it was similar to last year in performance. The rear is also a wave-style rotor but has the more traditional wave form.
New wave-style brake rotors grace the front and rear wheels for less unsprung weight. The 250mm front looks like one of Kawasaki's petal-style rotors while the 245mm rear has the traditional KTM waviness. The dual-piston caliper up front got a reworking. It's now made from forged aluminum instead of a casting, and it holds 22.65mm pistons versus the 27mm pinchers of 2006 and correspondingly smaller pads. A new push-rod lever is supposed to offer a more direct action and better lever angle for your right hand, but truly it felt the same as the traditional system under my glove.
I personally wasn't extra-impressed with the front binder on the '06 model, and I could hardly tell a difference in the performance of the new one. The shrunken 2007 version feels equally as powerful, but it was hard to discern much on the sandy Milestone MX circuit. To further test the brakes, I gave the bike a few extracurricular runs along the water truck access roads, but I still wasn't convinced they are a step forward. The deep sand would have made a drum brake feel stout so a more thorough braking evaluation will have to wait until our shootout.
kept the combination of a 756 rear and 739 front tires. The Dunlop duo added to the difficulty in testing in Milestone MX's deep sand. While the rear tire offered decent amount of drive, the hardpack front tire was less than ideal.
Trimming the fat and making the steering easier does make the new Yammie feel like a slimmer machine. Yamaha claims that the 3-lb weight reduction for 2007 makes the YZ the lightest Japanese 250F. If the weight reduction claim is accurate, the '07 bike should scale in at a tank-empty weight of 216 pounds, tying the CRF250 for lightest-in-class honors. We'll put the claim to test on our super-accurate digital scales during shootout season. So far the bike appears to have relatively steady aim.
Power output does feel a little more robust this year, but the big low-end tug just isn't there. The bike can still be lugged around, but it definitely likes to build some steam.
The motor is mostly unchanged from last year with the minor adjustments targeted at giving better throttle response and improved performance from the midrange to the top end. The internals of the 249cc, 5-valve DOHC motor are identical to the '06 powerplant, but Yamaha extended the tail pipe, revised the ignition mapping, altered the accelerator pump, changed the 37mm Keihin FCR carburetor settings and gave it a lighter magnesium clutch cover.
Changing the exhaust muffler is noticeable visually, since the end cap has a similar elongated appearance as the Pro Circuit cans used on Ricky Carmichael and James Stewart's factory bikes. Another strong reason for the change is to meet the upcoming AMA sound regulation changes which limit bikes to 99 decibels. Yamaha claims the new pipe meets the requirements. The tune is pretty muffled to our ear; we'll use a sound gauge to double-check during our comparo.
The rev-limiter remains at 13,500 rpm but I never found it. The only two sections long enough to gain any real speed were filled with whoops. One was a sweeping right hander with whoops small enough to get up on, but the straightaway was consumed by large, rolling mounds that were far enough apart that only the pro-level riders could skim. Either way, wringing out the YZ-F nice and long before snagging an upshift in the 5-speed tranny was tough to do on the tight course which limited me to the bottom three cogs. However, the bike does offer good snap at a turn of the wrist, part of which is due to the larger rear sprocket. Being a little shorter, the 49-toother helps keep the bike higher in the revs where engineers want it to be. The little motor sings into the upper rpm fairly quickly without hiccup or surge. Everything about the '06 engine was usable, and the new version keeps that attribute with a tad more oomph towards the top.
The new Yammie responds quickly to throttle input. Blasting out of corners is great fun, especially if you can keep the motor up in the revs.
Last year's press intro was at Honey Lake MX which was terrific for judging brakes, chassis flex, stability and power, but the elevation detuned the motor for our initial test. We eventually got the full picture during our shootout, but unfortunately the Yamaha had more trouble conquering the competition than it did Honey Lake's massive uphill.
Our first ride on the 2007 has left us feeling once again like we don't have the best initial understanding of what this bike has to offer. Hopefully the new machine will have better luck against the '07 crop of contenders. With the updates to this well-rounded model, especially the advancements in handling, the YZ250F stands a good chance of enjoying better results.
2007 YZ250F Specs:
249cc, DOHC, 5-Valve
77 x 53.6
37mm Keihin FCR
27.0 deg/4.6 in
250mm Wave, Dual-Piston
245mm Wave, Single-Piston
214 lbs Tank Empty
$6149 ($6249 White)
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