2008 Yamaha YZ450F Comparison

JC Hilderbrand | April 9, 2008
2008 Yamaha YZ450F
Any time the reigning champion goes from first to fourth with much of the same testing crew on hand you know it was a big year of changes.

2008 Yamaha YZ450F

Rank: Fourth
Categories Won: Suspension (tie)
Best Feature: Pillow-top KYBs, Shorty Silencer
MSRP: $7099

Half of our testing staff from 2007 returned for this round of moto throwdown but the YZ450F finds itself in a vastly different light. There were several things that contributed to the rapid downward slide – mostly major upgrades by the competition. The 2008 YZ-F is fairly unchanged and it has subsequently fallen behind in the ultra-competitive market.

Yamaha revised the intake and exhaust port cam profiles and intake port shape in an effort to improve low- and mid-range power. None of our testers noticed it. The YZ-F is still a screamer and the power really begins to boil on as the revs climb. Torque and horsepower are both underwhelming until about 7000 rpm, but the over-rev is something to write home about. For some of our less experienced riders it’s difficult to convince the ol’ gray matter to rev the bolts out of a 450. That isn’t necessarily the case with the Yammie. All our riders, fast and slow, commented that the bike not only likes to be ridden up high, but is easy to live within those ranges.

The Yamaha turned its back on the competition for one year and it was overtaken by a tidal wave of technology. Regardless  the YZ450F has enough features to be competitive anywhere with a few tweaks.
The Yamaha turned its back on the competition for one year and it was overtaken by a tidal wave of technology. Regardless, the YZ450F has enough features to be competitive anywhere with a few tweaks.

Modifying the motor to get better response off the bottom might be as simple as a pipe and silencer with the accompanying jetting changes. But, we hate to think about losing the awesome punched-cone muffler! It’s easy on the ears and eyes for us. By using the new design, Yamaha claims to have shaved over half a pound and shortened the length by 35% or six inches. We’re not convinced that it’s the best thing for the motor, but it definitely appeals to us aesthetically by ditching the trademark snorkel of modern 4-strokes.

Sliding around in the cockpit is one of the finer points of the Blue life. As we’ve come to expect, navigating the rider controls is simple, though not necessarily the favorite layout for every rider. The Yammie definitely has the most unique feel in the saddle. Part of that is the aluminum chassis design. Where the other three OEMs use oversized tank spars, the Yamaha is much more slender in appearance and feel. Add in that the rider is perched on a massive set of 55mm footpegs and it’s no wonder YZ-F pilots like to get aggressive with their body input.

The chassis complements its Kayaba suspension – one of only two areas that were able to tie for first place in our evaluations. The first word out of every tester’s mouth after dismounting the 450F was “plush.” There’s absolutely no denying that Yamaha has figured out how to soak up the bumps and chatter of a motocross track better than any other. With such soft action from the 48mm fork and titanium spring on the rear shock it was expected that big jumps, flat landings and sharp impacts would blow through the stroke and bottom the easy-going suspenders. Nothing could be farther from the truth. Our fast guys did manage to find the bumper stops, but even when maxed out the KYB units retain a progressive and controlled feel that rarely jars the rider. Speed-sensitive damping on the fork is terrific on those square-edged holes and sharp hits, completely eliminating mid-stroke harshness.

The KYB suspension is absolutely terrific. Easily the most forgiving and plush of the group  it still handles frame-dragging impacts with relative grace.
The KYB suspension is absolutely terrific. Easily the most forgiving and plush of the group, it still handles frame-dragging impacts with relative grace.

As high as we are on the suspension, we’d like to see a little improvement on the transmission. Super-easy clutch actuation, good feel and fade resistance are all great, especially considering that the weak low end requires plenty of fanning, but there are some gaps in the gearbox that cause trouble. Upshifting from first to second and second to third revealed some false neutrals that caught us off guard on more occasions than we’d have liked. Some of that could be eliminated by changing the final gearing. With so much over-rev on tap, all of our riders were willing to sacrifice a little on top for some extra punch and gear-pulling power down low. Unless you ride wide-open terrain all the time you will want to add some teeth to the rear.

A fourth-place rank definitely didn’t make all of our testers happy, but there is still plenty for the Tuning Fork company to hang its hat on. The biggest points of contention on any bike are the engine and suspension. With the 2008 configuration the motor is right on the verge of being as completely thorough as the Kayaba sticks. Once that happens it will all fall into place for the likable Yammie. Excellent brakes and increasingly attractive styling are some of the little things that will help make this bike a great overall package for a lot of riders.

Rider Rants

Alvin Zalamea:
The Yamaha felt like it had a sock in the airbox or something. I just couldn’t get the thing going. It felt so slow compared to the others. Maybe a quick fix would be a pipe and muffler.

I think the other manufacturers are going somewhere with the aluminum perimeter frame, but I do give Yamaha credit for trying. This bike turns better than it did last year, but not quite as well as the others. It’s a rear turning bike but it’s very stable. Glen Helen-type tracks are where this thing shines, anywhere it gets rough.

JC Hilderbrand:
I think I can run over just about anything on this bike and not get out of shape. Those Kayabas are so good it’s unreal. Maybe for a fast guy they’ll be too soft, but the initial plushness and progressive feel as it nears the end of the stroke are awesome. Even when it does bottom the jolt isn’t nearly as harsh as the other bikes.

In stock form the motor definitely isn’t as robust as the others. It runs really well when the revs are up, but it needs some gearing changes to shorten the gaps in the first three gears and give the motor some help at low rpm.

Adam Waheed:
Without a doubt the Yamaha’s power is the most easily accessible, especially for a novice rider. Next to the Suzuki, the YZ-F’s engine felt the smoothest. The soft, easy-to-use engine doesn’t tire the rider out as much as the other bikes. However, it does feel like it’s the slowest revving of the group.


JC Hilderbrand

Off-Road Editor| Articles | Hilde is holding down the fort at MotoUSA’s Southern Oregon HQ. With world-class dirt bike and ATV trails just minutes away, the hardest part is getting him to focus on the keyboard. Two wheels or four, it doesn’t matter to our Off-Road Editor so long as it goes like hell in the dirt.

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