ONE PHOTO & ONE STORY: COOPER WEBB’S 2015 STAR RACING YZ250F

On May 4, 2016 Last updated Jul 30, 2016

By John Basher

With the 2016 AMA National Series nearly upon us, I thought it would be interesting to look back at one of the National-winning 250 bikes. Maybe you’ll remember how Cooper Webb, the pride of Morehead City, North Carolina, was on a hot streak during last year’s 250 West Supercross series. Webb won six main events in a massive rout and captured his first Pro title. Unfortunately, Cooper tweaked his ankle at the Las Vegas finale and sat out the 250 East/West shootout. Several weeks later he tore several ligaments in the same ankle during the second moto at Hangtown. He was forced to the sidelines for Glen Helen through High Point. The downtime resulted in MXA getting the opportunity to test Cooper’s Yamalube Star Racing Yamaha YZ250F.

In general, 450 factory bikes have more works trickery than in the 250 class. That’s because the 250 teams are limited by the AMA rulebook. Regardless, the premiere 250 efforts are stocked with some of the preeminent mechanics and engineers in the pits. These few find ways to skirt the rulebook in order to aid their sponsored riders by providing maximum performance. It’s genius, really. Off the top of my head I believe guys like Kristian Kibby (Geico Honda), Zach White (Pro Circuit Kawasaki), and Brad Hoffman (Star Racing Yamaha) are excellent at getting the most out of their race bikes. Mechanics are also instrumental in the process. There are too many great wrenches for me to list here.

This leads me to Cooper Webb’s YZ250F, which was easily one of the most impressive 250 race bikes in the paddock last year. What was so special about Cooper’s Yamaha? Here’s the short list:

1. Factory parts. The billet aluminum hubs, spokes and spoke nipples come direct from Yamaha Japan. Webb’s gas tank was thinner and held an additional 1-1/2 liters of fuel. The gas tank thickness isn’t noticeable to the casual observer.

2. Front brake. Star Racing discovered in testing that joining different brake parts together resulted in an optimally performing front brake. Webb’s front master cylinder came off a 2004 Honda. The caliper is from an 11-year-old Yamaha. Cooper’s mechanic, Eric Gass, cut off the plastic sheathing around the stock brake line. Standard brake pads and a 270mm Braking Batfly rotor completed the package.

3. Forks. Keep in mind that I’m writing about Webb’s 2015 National bike, meaning that Star Racing Yamaha might have a completely different setup heading into Hangtown in a few weeks. Cooper had used Kayaba’s Factory Kit forks, with Kashima-coated outer tubes and DLC-coated inners. The 32mm anodized cartridge rods were designed to stand up to the rigors of motocross, and the whole system was a PSF (Pneumatic Spring Fork) air fork design.

4. Shock. KYB’s triple adjuster shock provided the ability to tweak the low- and high-speed compression damping separately, as well as the low- and high-speed rebound.

5. Radiators. Star Racing re-welded the stock radiators at every seam, and included backing braces for strength. They used a 1.8-bar high-pressure radiator cap to prevent coolant boil-over. Believe it or not, the Star team shaved down the frame where the radiators mounted to draw them in 5mm on each side. That modification narrowed up the cockpit for Cooper’s legs.

6. Subframe. Eric Gass cut 10mm off the subframe to lower the rear end. Webb liked to run 5mm taller Raptor titanium footpegs, as the added height helped fit his 5-foot-7 frame.

“AFTER WE FIGURED OUT HOW TO WORK WITH THE 13/47 GEARING COMBINATION AND SAYING A FEW HAIL MARY’S, WE LEARNED THAT WEBB’S YZ250F WAS A BEAST FROM THE MIDRANGE ON UP TO THE TOP END.”

Would you like to know some other interesting facts about Cooper Webb’s 2015 AMA National Yamalube Star Racing Yamaha YZ250F? Read on.

GYTR, Yamaha’s in-house accessory and performance division, took care of the YZ250F cylinder head, valve train, porting, clutch basket and ignition cover. Webb preferred the stock internal clutch hub, pressure plate, clutch plates and fibers, as well as stock YZ450F clutch springs. A GET ignition helped the engine tech to tune the engine from race to race. CWI trued and balanced the crank, and Xceldyne titanium valves were used. The engine lived on VP Racing MR-Pro 6 fuel. A FMF specially made exhaust completed the package.

Contrary to what you’re probably thinking after reading the laundry list of modifications, you can build your own Cooper Webb Star Racing YZ250F replica. Things like LightSpeed’s carbon fiber skid plate, GYTR parts, Takasago Excel A60 rims, X-Trig triple clamps, Pro Taper bars and grips, Braking rotors and D’Cor graphics are some of the items available to the consumer.

How did Cooper’s bike run? After we figured out how to work with the 13/47 gearing combination and saying a few Hail Mary’s, we learned that Webb’s YZ250F was a beast from the midrange on up to the top end. We really enjoyed the Frankenstein front brake and came away impressed with the how planted the bike was in a variety of situations. Most of all, we were just happy to spend quality time on one of the most impressive bikes this side of the pond. Read the full breakdown of Webb’s 2015 YZ250F outdoor bike in the September 2015 issue. I can’t wait to see what changes the team made for the upcoming National series.