Chad Wienen’s 2012 racing season was made up of 50 percent confidence, 50 percent guts and 50 percent pay back. Going into the season, it looked like the numbers just wouldn’t add up, but when the smoke cleared, the result was the AMA ITP/Moose National MX Championship.


                One year ago, no one could have predicted such an outcome. Chad was recovering from a broken back, he had just been dropped from the biggest racing team in the ATV world and no one was hiring. In the budget-crunched world of quad racing, the only opportunities available are the ones you make for yourself. Chad looked around and saw that all the pieces for a championship effort were laying in different places, waiting to be assembled. One of those pieces was the Yamaha YFZ450. He had seen Pat Brown ride one at the pro level without mishap and knew it was championship material, even if it had never won. Another piece was engine tuner Ryan Cox. Cox had been a major factor at Team Kawasaki, Team Yoshimura Suzuki and Team Motoworks Can-Am—basically a complete list of the greatest teams in ATV racing over the last five years. Put Wienen, Cox and Yamaha all together, and amazing things could happen. They did.

Unlike the quads that won the last five national MX titles, this machine wasn’t assembled in a factory race shop. Chad Wienen’s YFZ450 is the product of a private effort.

Quad racing is expensive. “We blew through our parts budget for the whole year before the third race,” says Ryan Cox. “Yamaha really stepped up to help when we started winning.”


Chad’s program had to be built from scratch. No single entity had the budget to support the effort, but Donnie Luce at Yamaha saw the possibilities. He scraped together the funding for the quad, a parts budget and some contingency money. Maxxis came on board and pretty soon Wienen Racing was born with just enough resources to do the first few races. They would have to win in order to stay in the game.
               Winning in the brutal world of ATV racing requires more than just talent. It takes power, and a lot of it. The starts are critical and a production quad with off-the-shelf hop-up parts could never hope to compete on the National level. Cox had been an insider at Yoshimura and Motoworks when those teams were searching for power, and he had no illusions about how much work was involved. When Wienen Racing was formed, he had just a few months to accomplish what took Can-Am and Suzuki years.
               His first stop was Tom Malaska, who has an engine shop in North Carolina. Malaska is heavily involved with roadracing motors and uses a flow bench to analyze a head’s performance. Cox started with about five different heads; all got five-angle valve jobs and different port shapes. Between the flow bench, the dyno and Wienen’s own test sessions, they settled on a head design with a high-compression CP piston. Coming up with an EFI/ignition map is even more time consuming. They started with a programmable Vortex ignition and ran through dozens of maps. “The preprogrammed Vortex maps are actually pretty good,” says Cox. “They would be fine for most riders with most engine configurations. Even though we had our own head, we ended up making only a few changes.” The stock Mikuni throttle body was bored out, and the whole EFI system is fed by a Fuel Customs airbox and K&N filter. Actually, there’s not much of an airbox left; the filter is out in the open for most races. If it’s muddy, Cox has an enclosure that bolts in place quickly. The standard battery box is used, but cut down to occupy less space. At the other end, an FMF pipe is used, with a special core to pass the 96 dB sound test. 
                Nothing is needed for the bottom end of the Yamaha  motor. It’s the most reliable design in the ATV world, which was quite a relief for Cox and Wienen. “With other motors, I’ve had trouble when they make a lot of power. The crank halves will start walking off the crank pin after a few races. And the gearboxes don’t last—it took different heat-treating processes to make them last a single race.  With the Yamaha motor, I tear apart the bottom end after every race, and everything looks new. Chad’s practice quad still has the original gearbox.” The only non-stock parts below the base gasket are the Carrillo rod and the Hinson BTL (slipper) clutch.

Horsepower is crucial at the national level. You can’t  win without it, no matter how good you are. The Wienen Motorsports YFZ has a custom head with a five-angle valve job, a bored throttle body and a CP piston.

We got to ride Chad’s bike carefully before it went on display. Well, we weren’t that careful.

               In the chassis department, the first order of business is to slightly alter the Yamaha front end geometry. The top mounts of the upper A-arms are relocated so that the arms are parallel and steering is uniform throughout the suspension travel. Walsh has a kit for that and also supplies the A-arms, steering stem and swingarm.  Fox air shocks are used in front with custom valving. A Fox Podium shock is used with Walsh linkage in the rear.
               The stock spindles are used in the front—that’s a little unusual in the pro racing world. Most other teams have adapted Suzuki spindles to their respective front ends. The rear axle is a Lonestar, the nerf bars are Rath and the steering damper is a Precision.  All of that is fairly common equipment in the Pro world, but the front brake master cylinder is something we haven’t seen before. It was made by a French company called Baringer that specializes in Supermoto. Frenchman Jeremy Warnia had one on his quad and Chad was impressed.  
                Maxxis tires are mounted on DWT wheels. Nothing unusual about that, aside from the fact that DWT is owned by the same company that owns the Motoworks team, Chad’s arch rival. “We’re just interested in using the best stuff,” says Cox. “Winning races is our only priority.”

               When Chad Wienen came out west to accept accolades at the AMA Awards Banquet, he brought out his Yamaha for display purposes. Big mistake. The Dirt Wheels staff descended on him like locusts in riding boots. We weren’t about to let the national champion’s quad come so close to our riding zone without taking it for a spin. We could hear the apprehension in Chad’s voice “…but it looks absolutely perfect right now. Can’t you ride it after the banquet?” No deal. We knew our best shot was to intercept the YFZ as soon as it rolled into town. Besides, we know Cox’s work. The machine always looks perfect.
              So on the Friday before the Yamaha was to appear in a swanky banquet hall, we had it at Racetown in the high desert of Southern California. We weren’t completely without sympathy. We promised only a short ride and swore not to wreck the graphics.  Frankly, it wouldn’t take much time to tell us the truth. Two years ago, we got a chance to ride the three top national quads of the day: the Yoshimura Suzuki 450, the Motoworks Can-Am and the Baldwin Motorsports Honda. What stood out in our minds from that encounter was the amazing motor of the Suzuki. Since then we’ve ridden other top quads including John Natalie’s 2011 championship winning Can-Am, but nothing impressed us as much as that Suzuki. When it was retired from racing, it was on top. Could the Yamaha compete with our idealized memory  of the Suzuki?
                Yes. Wienen’s YFZ450 is an amazing machine. When you do a warm-up run, it seems fairly tame. It runs cleanly off the bottom, doesn’t cough and isn’t even very loud. It seems like an ordinary race quad. But when you gas it—[really] gas is—The Yamaha has a completely different personality. It flat boogies. What really sets it apart from most other race quads is its crazy overdrive. After yanking your arms out with a massive mid-range surge, it just keeps going, revving higher and higher. Clearly, the Vortex ignition has a higher rev ceiling than the stock ignition. The Yamaha can get away with that. It’s no secret that the YFZ450 is stone reliable in stock form, so that gives an engine tuner more freedom to push the limit. A DS450 or a TRX450R could never get away with this kind of rpm. 
               Once you get past the shock of the motor output, the next most attention-grabbing aspect of the machine is its sheer perfection. It rolls freely, it tracks straight, it steers lightly and everything is crisp and clean. Ryan Cox is a perfectionist. We know of other tuners who can come up with phenomenal horsepower numbers, but many of them can’t be trusted to tighten a chain. Cox does great work in both theory and in practice. It’s no wonder that Wienen had such an incredible record in 2012. When you don’t have to worry about your machine, you can devote all your concentration to winning races.
               We admit that we didn’t put Wienen’s quad through a very grueling torture test. We already know that it handles good enough to win a national championship, and we certainly can’t test it at that level. But we had a blast. And we also learned that it doesn’t necessarily take a factory effort with a massive budget to produce the best racing equipment. It can be done on a shoestring with just a handful of people. They just have to be the right people.




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