Story By Adam Booth · Photos by Drew Ruiz
Here at Dirt Rider, we pride ourselves on showing you the pinnacle of SX and motocross machinery and highlighting what exactly makes these bikes so special. Here we bring you an inside look at the baddest of the bad from the 2013 Lucas Oil Pro Motocross Championship, except with a twist: we shot these machines after a brutal moto, still steaming and fresh from the dirt. We then chatted up the stressed out mechanics to get a little insight as to what kind of abuse takes place at the highest level.
With only two weeks before the start of the outdoor season, James Stewart jumped the JGR Yamaha ship and agreed to ride a Suzuki RM-Z450 for free until his official Suzuki contract starts in 2013. Don’t feel bad for James because he isn’t cashing Suzuki checks; most people would be in a state of bliss to make the money he does from his other sponsors. His bike, a yellow work of art, is based heavily on the previous Suzuki factory rides piloted by Ryan Dungey and Chad Reed, with Reed being one of the best testers in the pro ranks. James has made no secret of his positive feelings for the Suzuki compared to his old Yamaha. Here are some of what makes his new factory bike so special:
There are only a few parts on Stewart’s Suzuki that the average person could own: the frame, the swing arm, engine cases and the cylinder head. After that every component comes from the aftermarket or Factory Suzuki in Japan, the latter of which are all one-off items.
The wheels use works aluminum hubs with standard spokes and a finer thread into the nipples. Dunlop rubber wraps the wheels and to avoid getting a rear flat a mousse replaces the inner tube. The rear wheel sports a 230mm works rotor, a standard caliper with different pads, a different piston and all titanium hardware. The rear axle is made from special steel with stronger coatings. The front brake rotor is 280mm with a works caliper and works brake pads. The brake pedal is a one-off item with a titanium tip and the master cylinder is works from Japan. The footpegs are titanium as are the brackets that hold them. All the bolts on the bike are titanium except the top shock bolt, which is steel, and the bolts that hold the shrouds and seat (they are aluminum). The radiators on the #7 bike are wider than stock, pulling in more air and causing the shrouds to stick out a little more. The engine of a factory bike is top secret but we can tell you that the internals, like the crank, transmission, valves, cam and piston are all works, producing the big power Stewart demands. His mechanic told us Stewart runs a gear higher than other pros. The works oil pump covers hold more capacity and flows more oil to keep the temps down. To ensure the bike makes it through a moto without running out gas, a larger, custom carbon fiber tank replaces the stock aluminum unit. Works triple clamps hold the finest 49mm forks Showa has to offer and the works Showa shock operates through linkage that may look stock but it is altered from the factory. The Yoshimura exhaust system is specially built for the team and Stewart’s bike. The seat is also lower than stock, giving more room when standing.
“The best part of the job is when your guy wins; the bike is a labor of love for me. I work on the bike so much and I look at it like it is my bike and the guy rides it once a week. If you don’t like doing this, it is the wrong job to be in. There are so many hours and sometimes there aren’t enough hours in the week to do this job. It’s been 15-17 hours everyday for the last two weeks just to make it to Hangtown.” —Stewart’s mechanic Lee McCollum
With Ryan Villipoto watching the nationals from the sidelines, all available attention from the Kawasaki crew is focused on Jake Weimer, and it is paying off with strong finishes. Weimer is finding his groove aboard the powerful green machine and while he isn’t setting the fastest lap times, he rides smart and strong throughout each moto.
“We really don’t change a lot of parts on a regular basis. We run our engines for two races and then rebuild them. We have six motors in rotation, three motors for each rider, and there are always two on the truck. After the second race we’ll take the motor out and ship it back early in the week to get rebuilt. Another engine then gets sent back to put on the truck. There’s always one motor in the bike and one in the truck at all times. The chassis comes apart every week. Usually halfway through a season we’ll change the frame and swingarm, but we don’t have any real reason to do it. But as far as parts, most of our stuff lasts a long time. Sometimes we’ll change the swingarm because it gets dents and scrapes from other riders’ footpegs and rocks, but other than that it’s really just cosmetic work.”
“I’ve been around racing for a long time so I’ve seen some mechanic mishaps. Most commonly, I hear about mechanics forgetting to put oil back in the transmission. When they drain it pre-moto, sometimes they get sidetracked and forget to put it back in. I’ve also heard of some people forgetting to reattach electrical wires so the bike has mechanical problems. Sometimes the occasional nut or bolt comes off, but nothing so major it ends someone’s race.” —Weimer’s mechanic Dana Wiggins