2010 Yamaha YZ450F Print E-mail

Words & Photos by Chris Worden
www.motocross.com
Twelve years ago Yamaha challenged the world of off-road racing by introducing the YZ400F, a four-stroke motocrosser with the brawn to challenge two-smoker dominance in that sport. A short few months later, Doug Henry piloted that very bike to an overall victory in the Outdoor National series and it was clear that Yamaha was years ahead of the competition. Since then all of the major manufacturers have introduced competitive four-strokers, challenging each other to come up with something new and interesting. After many years – Yamaha told us three to five—of testing and development, Yamaha unveiled the radically re-designed 2010 YZ450F.

   

ImageWe told you a little about the bike in the October issue (see News, Clues), but here are more details. The engine is actually angled rearwards, and the cylinder head is now turned around, Cannondale-style, with the exhaust exiting the rear of the cylinder head and the EFI system and airbox up front. That gives the straightest path possible for the intake for the best flow: that means mo’ powa’. The cylinder head gets a little bump in compression, but loses one of the titanium valves: it’s now a four-valver. To accommodate the new reversed intake design, Yamaha has reduced the size of the gas tank (1.6 gallons vs. last year’s 1.85 gallons) and slid it underneath the seat. The new airbox sits directly below the fill cap on the tank and stays clear of the dust that is kicked up from riding. The gearbox still has five gears, but the components have been upgraded for better feel.
Of the revisions to the suspension, the changes in the rear of the bike seem to be the most drastic. Now that there’s no airbox to accommodate in the rear of the bike Yamaha has been able to mount the rear shock directly in the middle of the machine instead of offset like the 2009, which leads to a smoother, more balanced feel to the rear end. The shock also benefits from a larger piggyback reservoir, as well as a larger piston (from 46mm to 50mm in ’10). The front fork is a speed-sensitive KYB unit with 10mm more travel, and the frame is also all-new, with a “bilateral beam” design made of a combination of forged and extruded aluminum pieces. It all weighs in at 245 pounds gassed up: seven more pounds than the 2009, but who’s counting?
ImageYamaha sent me out to Budds Creek, Maryland—where Doug Henry rode to victory on his ‘98 YZ400 after breaking both arms the previous season—to experience the new bike in person. It didn’t take many laps around the track to realize that these new features do translate into a different overall feel. The new rearward-slanted engine as well as the bilateral frame puts the center of gravity much lower than the previous model. It’s like having ballast between your boots (this is a good thing). It took a while to get used to, but once I got the feel for it, diving the bike into big, rutted-out turns became much easier. Handling on this new machine is superb, but different; it takes a few laps to get the feel for, but once you figure it out, it’s a dream.
One of the main things that the Yamaha staff wanted to reinforce was that the new design, with its emphasis on mass centralization, led to a bike that’s easier to ride. From my limited experience at Budds I’m sure they’re right, though I look forward to getting the bike out on the track in Southern California where I’m more familiar with the terrain. Overall, we left Maryland very impressed with Yamaha’s new YZ450F. Yammie made some big promises with these new design elements, and I’d say that the years of testing and development on this bike paid off: promised kept. Let’s hope you don’t have to break your arms to precede your personal comeback.
 
[ Back ]