Motocross Test: 2009 YAMAHA YZ450F

 Experiments are for other companies and better times, Yamaha is sticking with what works

Fortunes turn quickly in the motocross world. The Yamaha YZ450F was on a roll. The 2009 version won everything that it was assigned to win in Pro racing. It was the basis for the bike that Grant Langston used to clinch the National MX Championship and it carried that momentum right into the 2008 Supercross Series where Chad Reed dominated. But now, things are different. You’d be hard pressed to find a Yamaha in the top 10 of a current National.

      Of course that’s why it’s dumb to think that Pro results have any value in choosing a new bike. The YZ450F that won with Reed and Langston is the same YZ450F that can’t buy a podium now. It remains the solid, if unspectacular, choice in the 450 hierarchy. The new version was the first 2009 model to reach showrooms, and it has a surprising number of significant if not flashy changes.


      With Suzuki, Kawasaki and Honda all going to fuel injection, it seems there’s strength in numbers. Yamaha has the technology to do the same, but didn’t go there for a couple of reasons. First, the advantages of EFI are minimal right now. The Suzuki gained weight and while the fuel delivery system’s performance is good, so is that of current carburetors. Two, it’s expensive. In the current economic landscape it just didn’t make sense to rush something into production that would increase the cost of the bike.

      Down the road there’s a 99.9 percent probability that Yamaha will inject. But they didn’t see the upside in doing it now. Instead, the YZ got a fair number of nearly invisible changes, almost all in the chassis department. Yamaha engineers got a little intense about shedding unsprung weight this year. The bike got a new swingarm, rear hub, axle and linkage, and it’s all about being lighter where it counts. When a big bump knocks the wheel upward, various Newtonian laws make it want to continue going upward even after the bump is handled. That’s why we need compression damping. But less compression damping is required when there’s less mass in that upward motion. Oddly enough, Yamaha didn’t decrease damping or change anything about the shock, instead leaving that to you and your screwdriver. The new hub accepts a 3mm larger axle, so now it’s the same size as a Honda’s at 25mm. The new hub still has the bolt pattern for the disc and the sprocket, and you can even retro fit an older wheel if you have an old axle and blocks.

      The new swingarm is lighter and more flexy on a vertical plane, where flex can be a good thing. It’s said to be more rigid side to side. And the new linkage has the same lever ratio as before; it just mounts differently to the swingarm. There are some welcome changes on the other end, too. The top triple clamp now offers two different mounting positions for the handlebar clamps. If you’re a KTM rider, you know the routine. The bar clamps can be mounted forward or back, plus they’re offset so they can be flipped forward or backward. The clutch lever has a new on-the-fly adjuster and the reach to the lever is now adjustable. But if you’re looking for more power,  you won’t find it here. The Yamaha has no motor changes for 2009, aside from some minor alterations to the shift forks and an additional mounting hole for the stator. Yamaha made a commitment to lower sound levels last year with its semi-mechanical muffler and is sticking with it. That has a predictable cost in horsepower, but in stock form, theYZ450 is very quiet.


      For the record, the YZ450 is the slowest bike in the class.  The power is soft on the bottom and it tries to catch up late in the mid-range. On top it tapers off a little early. A little. Keep in mind that we’re talking about 450 MX standards. It’s still a lot of bike. And the soft power is 100 percent a result of the muffler. We know a number of people who put loud pipes on their 2008 YZ450s only to return to stock. It turns out that most people can go faster, longer on a 450 if you take away a little power. The human factor is the weakest link and it’s unlikely that many riders on stock YZ450Fs ever got passed because of a power deficit. The straight would have to be long, the hill would have to be steep, traction would have to be perfect and the other rider would have to do everything right.

      But on the other hand, you might occasionally miss an opportunity to make a pass when you have all those things working in your favor and the other guy makes a mistake. And then there’s the start. No matter how you look at it, power always helps off the line. So let’s say you decide to eat your vegetables, do lots of time in the gym and get an aftermarket pipe. Then the result is a bike with a powerband very similar to that of an ’08 Honda. The power hits hard and low and there’s enough over-rev to stave off that last upshift near the end of the straight. Now you have the power to hang with anything in the class. We would still point out that the power isn’t as smooth and controllable as an ’08 Kawasaki or Suzuki. On both of those bikes you can upshift and ride happily in the lower revs zone where things are easy to handle. On the Yamaha it’s a little lurchy down there.

      We left the jetting stock on the YZ. Interestingly enough, we tried several aftermarket pipes on the bike and never had carburetion issues. The bike never flames out, never pops or hiccups. It’s understandable why Yamaha engineers backed away from fuel injection. They finally got carburetors right.


      In chop, that’s where. The Yamaha already had great rear suspension. Take away almost two pounds of unsprung weight and it only gets better. The shock feels a little soft when you first climb aboard, but after a few laps you realize that it only feels soft in a good way. It responds to nickel-and-dime bumps and gives you a comforting insulation from track garbage. But it doesn’t extract the usual price of soft suspension, at least not severely. It stays level in turns, it rarely bottoms and remains a stable platform in most situations. As always, some fast riders might want a little more spring. But you shouldn’t automatically assume that. Like we said, it feels softer than it is and that titanium rear spring is much too nice a piece of metal to put on the shelf.

      In front the ’09 suspension is identical to last year’s stuff. That’s fine with us, too. We liked it then, we like it now. It’s perfectly balanced with the rear. If you weigh around 170 pound consider yourself Yamaha’s bullseye. That’s who the bike is set up for. Heavier riders who need more preload in the rear might throw off the magic balance in the rear, but nobody considers the suspension a weak point, from big and fast to short and slow.

      Riders are much more likely to complain about the way the YZ turns. In 2007 it was a major issue, but Yamaha made changes in 2008 that cured it for about half the YZ riders on the track. The ’09 turns exactly like the ’08. When you go with the flow and don’t fight the front end, you’re in the YZ’s sweet zone and everything is good. It’s when you force a turn or a line shift that the bike is unhappy. So it all depends on your riding style, the smoother you are in turns the better the bike works. As speed increases, the bike gets better and better. It’s a Yamaha all right, stable and predictable.


      Yamaha’s message is mixed. On one had it seems that the company wants to put the aftermarket out of business. All of the parts are great; you can’t buy better wheels or handlebars. You’d be nutty to replace the top triple clamp and the levers had better be good and bent before you look elsewhere. But on the other hand it seems that Yamaha is letting aftermarket pipe companies get back into the game by making them part of the product planning. Everyone should know before they lay money down for a YZ450F that the final state of tune is up to the buyer. You always can make it faster, louder and harder to ride.

      But it will never be quieter.


Yamaha gave the YZ dozens of little changes that add up to, well, dozens of little changes. If you liked it before, you’ll like it still.


The YZ450F is the quietest motocross bike you can buy. Most riders should leave it that way, but few will as soon as the discover how much power an aftermarket pipe can deliver.


Yamaha made no changes to the 2009 YZ450 motor, aside from minor things like shift forks and the stator backing plate. It’s still a great motor.


The 2008 YZ450 probably had the best suspension in the class. Now it has the second best.


If you’re smooth and let the bike do all the work, you’ll fine the YZ’s sweet zone in turns. If you fight it, it will fight back.


Comments are closed.