GNCC Pro Ride: Four-Stroke Tech Preseason Testing

After netting a pair of top-10 finishes and Rookie of the Year honors, Mickey Dunlap's Four-Stroke Tech (FST) racing team had what most would term a successful season. Always looking to improve, Dunlap and crew immediately set out to increase their chances for the 2005 campaign. Their plan: Sign a gang-load of talent, enlist the support of numerous companies with proven products and spend lots of time in the R&D shop over the winter so that even the most-power-hungry rider would feel sated.

While the initial mount of choice among GNCC competitors was the race-ready Yamaha YFZ, there has been a slowly rising number of Honda TRX-mounted competitors showing up, as tuners and shops have had more time to transform the tame stocker into a worthy racing mount. With the start of the 2005 season looming just ahead, there's precious little time to choose and test your machinery before the first gate is lined up. What's a racer to do? Ask 10 people around the paddock, and you're likely to get 12 different answers as to what is the smartest path to take. Luckily for Dunlap's racers, he had already been hard at work preparing both Yamaha and Honda machines for two of his riders who had already made up their minds regarding their mounts for the season, allowing those on the fence to sample the final products back-to-back before making their selection.

When we got wind the FST team would be holding an under-the-radar test to let its riders try both of the shop's fire-breathing configurations of GNCC race machinery, we knew immediately we would have to gate-crash this party. As an early supporter of four-stroke race quads and as a former racer himself, Dunlap would be unable to resist tinkering with the bikes over the winter break, and we had to see what the genesis of his off-season efforts would be.

Before the coolness of winter had subsided, FST had ported, bored and stroked the motors to increase their output. Yamaha's compact motor had been enlarged to 500cc, while the Honda had even more room for expansion and now boasts 530cc of displacement. Thanks to FST's ingenuity, the two motors grew more than would be possible by just enlarging the cylinders; each stroked motor required a good deal of head scratching and reconfiguring to make everything fit and retain the reliability needed for the race machines.

Clad in our full riding gear to disguise our identities, we clamored among the throng of FST riders, waiting for our turn to sample the quads. Gradually, we worked our way to the front of the line and got our turns at both machines among the GNCC illuminati. Each quad was similarly modified, receiving the full complement of suspension and engine mods. After spending quality time aboard the machines, it was funny to relate how different they are from each other, and how much of the stock machine's character each heavily modified racer retained.

Fans of the YFZ450 would appreciate the FST 500 version, because it's more, and we mean that in almost every way. It still has killer top-end hit but is even more vicious throughout the entire powerband. Clawing for traction, the YFZ can easily spin the rear tires and still wheelie with abandon. In order to finesse the quad through corners, the low-slung Yamaha seemed to respond best to digging in and taking an aggressive set during corners yet remained sensitive to fore-and-aft body positioning. Slide around the corner, aggressively feed in throttle (keep the front down!) and aim for the face of that table, and the Yamaha rewards with the flight of a jet fighter, carving through the air with a predictable and sturdy trajectory. The Janssen suspension hardware and Elka damping units do their job quite nicely, keeping the angrier YFZ planted and cornering as if it were on rails, even though the rear Maxxis rubber is frequently throwing a roost of soil while gnawing at the track.

FST's enlarged Honda still retains a light feel, but with much more midrange than the stock machine could ever dream of. Imitat-ing the smooth power delivery of the stocker, the 530 is deceptively fast, easing along at greater and greater velocity even though the Yamaha wins the drag race from a standstill. With its superb front-brake modulation, it's not uncommon for the high-riding Honda to loft the rear wheels entering a braking section. Around corners, the TRX-asaurus can be easily manipulated with just foot and heel input and can be set back to level with an extra touch of throttle. While more sensitive to left-to-right body position, the Honda is less sensitive to front-to-back transitions. During jumps, our testers felt the TRX was light in the nose, usually requiring them to approach jumps with their body weight far forward, then move their butt to the rear of the seat before landing.

It was hard to tell which machine was faster on the Durhamtown Plantation track in Union Point, Georgia, and rider preference seemed to play a large part. That said, here's what each of our staffers would pick.

Adam Campbell, ace lensman:
I love the monster power and killer delivery of the YFZ. Its low center of gravity and taut suspension make me feel right at home and remind me of my YFZ moto-crosser, except that Mickey's YFZ is an absolute beast and will pull hard in every gear. On the motocross track, the YFZ would have to be my number-one choice, but I think out in the woods, with the long races that are run, some of the Honda's attributes begin looking really good. I loved the TRX's low-effort, easy-to-modulate brakes, and I felt I could hold the throttle open longer with less drama thanks to them. The plush suspension and roomier ergonomics make it loads easier on my battered old racer's knees, which lets it edge out the Yamaha for woods duty.

Todd Canavan, Technical Editor:
I'm not used to riding the GNCC-style terrain back East, but I felt right at home with some of the Yamaha's moto-tendencies and got on with it right away. The power from the bigger motor was awesome and very addictive. While it might be overkill on some of the tighter GNCC courses, if you get a chance to pull the trigger, you will start reeling people in. I was less comfortable with the setup of the TRX--the high ride height made me less comfortable jumping--but it was still a very capable machine around the woods section of the course. Screw the softer ergos; train harder! I'd take the Yamaha.