Racer X Tested: 2007 YZ450F

Last year, Yamaha introduced their new-from-the-ground-up YZ450F with a lot of pride. And they should have. Yamaha started this four-stroke craze with Doug Henry and the YZM400 that he raced to victory at the Las Vegas Supercross finale in its debut season less than a decade ago. Since that time, the engineers at Yamaha have been on a mission to perfect that bike, which has become the YZ450F. Refinement was the goal when it came to the 2007 model and, even at first glance, it looks like Yamaha achieved their goal.

The 2007 Yamaha YZ 450F

The 2007 Yamaha YZ450F has a new clutch, a revised cam-shaft lift angle and overlap, a new exhaust system, wave-disk brake rotors, new Pro-Taper handlebars, a new radiator with bracing, new radiator louvers, new forged top, bottom and handlebar clamps, new seat-cushion design, and a longer rear shock. The changes to the engine and exhaust were aimed at improving the power characteristic of the motor and also meeting the new AMA sound requirements. More on that later.

The new brake rotors are lighter and, combined with a lighter chain guide, help to reduce the unsprung weight of the bike. The new clamps are forged to reduce flex; the seat foam is lighter to reduce weight; the rear shock is longer to improve the rider characteristic; the major bolts on the bike have all been changed to 10mm for easier maintenance; and the suspension clickers have also been changed from brass to aluminum for lighter weight and increased strength. The changes may seem simple, but they add up on the track.

Factory Phil gets the YZ450F dialed in

I recruited “Factory” Phil Lawrence for the day to help me with testing duties. Phil hadn’t ridden a YZ450F for two years and was excited to try the 2007 model.

“The last Yamaha four-stroke I rode was a 2005 model,” said Phil. “I really wanted to try last year's bike when it came out with the aluminum frame, but I never had a chance, so I’m pumped to ride this thing today.”
 
Factory set the sag and hit the track. When he pulled in, he had this to say:
“This thing is awesome. The motor pulls so hard down low. I could just keep grabbing gears and it would pull it, no problem. I'm very impressed with the feel of this bike. It's very light-feeling and easy to move around. It's also really stable at speed. Some of the other 450s have a twitchy feeling to them, but the Yamaha tracks really straight.”

I took my turn on the new YZ, and the first thing I noticed was how quiet it was. It sounded more like an off-road model than a motocross bike. The muffler is choked down to a very small diameter to reduce noise, and it works. At first, the lack of sound bothered me. I’ve always liked my bikes to have an ear-drum-damaging tone to them, and the YZ450F was very meek-sounding. I got used to the sound after a couple laps, though, and never thought about it again. In retrospect, I applaud Yamaha for taking the initiative to reduce the sound of their bikes. With riding areas closing around the country faster than you can say “99 decibels” (mostly because of the increased noise of four-stroke engines), the sport needs the manufacturers to be responsible, and Yamaha has taken the lead on the issue.

The new Yamaha is stable on the ground and in the air

Another improvement I noticed over last year’s bike was the handlebars. The new Pro-Taper bend is slightly taller with less sweep to it. They give the bike a roomier, more comfortable feel. The motor is the same smooth, strong powerplant I loved in last year’s bike. I could pull taller gears or rev the YZ to the moon and it continued to pull. The suspension seemed better than last year’s bike. The 2006 model was considerably over-sprung for a 160-pound rider. With just spring-rate changes, I was able to make last year's bike handle a thousand times better. Keep in mind, most 450cc motocross bikes are generally designed for a 180-pound rider. The 2007 had better action in the forks, and the changes to the length of the shock improved the feel of the rear end.

At the end of the day, Phil and I were very impressed with the new YZ450F. Will it be enough to win the Racer X Tested 450 Shootout? Stay tuned, because we are going to find out soon!

For complete details and specs on the 2007 Yamaha YZ450F and all of Yamaha’s motocross offerings, visit www.yamaha-motor.com.

The YZ holds a line effortlessly