Woods Racer
Woods Racer
Turning Suzuki’s little playbike into a big-time racebike
JIMMY LEWIS
HOW DO YOU TAKE A GREAT TRAILBIKE AND BUILD IT INTO A national-caliber cross-country racer? Suzuki started by asking Mike Kiedrowski, semi-retired motocrosser with championships in 125, 250 and 500cc outdoor nationals, to try his skills at off-road racing. Then, roadracing powerhouse Yoshimura got the call to develop the new DR-Z400 Thumper motor. Suspension would be works Showa equipment, no less. Seems easy enough, right?
The beauty of the Grand National Cross Country series is that for the AA (or Pro) class, there are literally no rules-sort of a run-what-yabrung format, with riders competing and winning on everything from 125cc two-strokes to Open-class four-strokes. Suzuki is no stranger to the series, currently running two RM250-based bikes, including Rodney Smith’s, the number-one plate holder. But Thumpers are big business off-road, and Suzuki wanted to prove ^ its new four-stroke’s worth. Racing • the DR-Z would be a true test of the bike’s versatility.
Right off the bat, the Yosh-built DR-Z motor was a firebreather, not hurting for power one bit. But at the end of a long three-hour race, it was a handful to control. As the series went on and Kiedrowski started learning the game of GNCC, that peak-power motor gave way to a more rideable package. I sampled the results recently, roosting around on Kiedrowski’s identically prepped, Californiabased practice bike.
The Yosh guys had a tight lock on engine info, but here’s what I know: Displacement still sits at 400cc, compression has been bumped slightly and, as you’d expect from the outfit that makes Mladin’s GSX-R fly, the cylinder head’s been treated to a free-flowing port job. Cams are reported to be stock, as is the valvetrain. The standard carb is used, but the pipe of choice is a titanium work of art that starts out small at the header and makes a step up about halfway to the muffler. Trickest part, though, may be the ignition with a different rev cutout and slightly altered timing.
Due to the increased power and expected tough times in deep mud, a lot of work has gone into the clutch. A Hinson billet basket is used, carrying Kawasaki KX500 fiber clutch plates. A Magura hydraulic actuator is added for its selfcompensating ability, keeping freeplay in check as the clutch takes abuse.
Though the frame remains mostly unchanged (except for the removal of a few unnecessary brackets here and there), everything hooked to it gets an upgrade, starting with special Showa suspension valved and set-up by off-road specialists RG3. Fork tubes are the same as stock at 43mm, but everything from the titanium-nitride coating to the softer springs to the much stiffer valving is different. Ditto the rear shock, with its billet-machined body, larger shaft and stiffer 5.6-kg spring. The forks ride in a 909 billet tripleclamp with a 909 BFB handlebar in a taller, more forward position than stock. Cycra bark-busters protect levers and fingers. Cycra also makes the radiator shrouds, a different shape from standard so they don’t stick out as much and grab brush along the trail. On the racebike,
Kiedrowski runs a WER steering stabilizer. All of the carbon-fiber is DSP stuff to protect the vital cases and brakes. Stopping is improved with DP brake pads and a 20mmlarger rear-brake rotor. Dunlop tires are used with mousse inserts to eliminate flats.
Posed alongside a standard DR-Z, the Kiedrowski bike looks like a top-fueler. But it starts right up with little fuss. In fact, the engine purrs down to a nice idle just like a stocker, except for the barky exhaust note. After riding the bike, it’s apparent that Kiedrowski’s concerns about rideability have been addressed. There’s just enough power to hook up without a ferocious snap or burst of power that would just uselessly spin the rear knobby. Perfect for the loose-traction situations that make up the majority of GNCC courses.
Kiedrowski says he has no problems reeling in other riders (mostly on 250 two-strokes) on the straights, but tends to lose a bit coming out of comers. The team will try a 436cc Thumper Racing cylinder and piston in some upcoming races to see if that adds pull off the bottom while keeping the super-friendly nature of the DR-Z motor.
In California, in the summer, there wasn’t much chance to abuse the clutch in mud, but compared to the stocker we had along for comparison, the action and shifting felt a lot more solid. With the handlebar farther forward and cut down to squeeze through tight trees, the DR-Z was roomy enough to move around on and much easier to climb hills with. Much of the credit here goes to the N-style gripper seat cover and the thinner IMS gas tank, which allows you to get forward and stay there.
The one place where there was no comparison to stock was in the suspension. Works stuff is magic, plush and consistent everywhere at all speeds. Typically with a production fork and shock, you get one or the other: big-bump absorption or small-chop compliance. With works suspension, you can have it all. Kiedrowski has his bike set up to ride high in the stroke to keep the footpegs out of ruts. The front end is purposely soft so it doesn’t deflect off small roots and rocks. The rear is a bit stiffer to handle big g-outs and the jumps on motocross sections. All in all, as good an off-road suspension as I’ve sampled.
The best part of this GNCC racer is that it shows just how good the production DR-Z “playbike” really is. With some well-chosen aftermarket parts-engine parts, pipe, etc.-it’s as much racer as most riders will ever need. As for Kiedrowski’s magic suspension.. .well, there are some special parts you just can’t get. Unless you’re running in the top 10 at a GNCC, that is-then they’ll find you. □
