Top Secret: SX Testing

Birth Of A Supercross Bike

From the April, 2010 issue of Dirt Rider

By Karel Kramer

Photography by Karel Kramer

Supercross does everything possible to make the first appearance of the top riders and machines a true spectacle. Often the bike and rider burst from obscurity into a bizarre double life: Reality on the track and in surreal-size on the diamond-vision screen. Bike and rider embody perfection as they dodge exploding fireworks, wheelie through smoke and fight a cascading soundtrack that dwarfs the crackle of a race-tuned 450cc four-stroke. Sponsors and teams make sure that the bike and rider are turned out in detail that can't possibly be fully appreciated from the stands. But at that moment, the bike you see is the tip of an iceberg-the bike on the SX track is the pinnacle above water, but it is supported by an unseen mass of money, testing, sweat and technology expended to arrive at the moment of unveiling. Dirt Rider wanted to follow the conception, birth and life of a brand-new 2010 SX weapon, and one of the Yamaha teams felt like the perfect subject. The new YZ450F is so radically new that even an existing Yamaha team would virtually be starting from scratch. To ferret out this information from an OEM team would have meant gnawing through layers of secrecy and combating corporate butt-covering, so that was out. On the other hand, we wanted a team that was doing far more than merely bolting on aftermarket parts. We quickly narrowed the possibilities to the Muscle Milk/Toyota/JGRMX Team. JGR is somewhat removed from under the corporate thumb by virtue of paying for its bikes and parts. At the same time, the expertise and resources available to the team are unrivaled. A late release of bikes and parts and typical North Carolina weather had Muscle Milk/Toyota/JGRMX techs scrambling to finalize settings and get team riders Josh Grant and Justin Brayton acclimated to the new machinery.

Top Secret Sx Testing Dirtbike Prototype Part

Every pure-blooded dirt rider has been waiting with sweaty palms for a ride on the 2010 Yamaha, but when JGRMX got a single bike in mid-October 2009, there were no parts. Team manager Jeremy Albrecht explained his thinking on the situation: "Riding the bike with no parts was pointless for us, so we tore the bike completely apart and sent the valves, piston and pipe to Xceldyne, JE and FMF so they could get started on race parts. In the meantime we put the fork and shock on the dyno to approximate our 2009 SX suspension settings so we would have a starting point. We rode the bike for the first time on November 12th." If you are paying attention, you will note that none of the team riders have even ridden the stock bike. Team R&D tech Spencer Bloomer explained that, "It wouldn't be safe for our riders to attempt an SX track with stock suspension. If the outdoor series were first, and we had the luxury of time, then sure the riders might have ridden the bikes stock, but not with the SX series rushing up at us." Our readers moan about pulling the linkage on a new bike to grease it before riding, and these guys tear a brand-new bike to bits and wait a month before riding it!

Next up was an unconventional decision on suspension. In the past the JGR bikes looked a great deal like factory Yamahas, and especially during the first year, we were amazed that a new team had the juice to get so many factory parts. Team leader Coy Gibbs shone a light on that. "We can buy Yamaha factory parts, and we still use the transmissions and titanium bolt kits, but eventually we'd like to be as self sufficient as possible. For example, we have our own brand of lubricants, we have a retail engine and suspension business, and we may have some hard parts for sale in 2010 as well. For 2010 the price of the factory suspension went way up, and we decided to look at alternatives. We could have used the 2009 fork, but the new shock is too different. We decided to use a Showa fork, and we have a proprietary shock built by JRI Shocks. JRI makes shocks for F1 and NASCAR, but some of the technicians got their start at Fox, and they have many years of motocross suspension experience but amplified with the resources and knowledge gleaned from automotive applications." When we were with JGR the shock was still a prototype in raw billet aluminum, but the plans were for a coated and finished version for Anaheim 1. The choice of a Showa fork made additional work for R&D tech Spencer Bloomer. "Showa doesn't have an axle lug for a Yamaha, so I had to design one on the computer, and the machine shop at the JGR NASCAR shop machined them for us. We had to design our own triple clamps and have those machined here as well."