Supersport 600s
SUPERSPORT 600s
When streetbikes get race-wise
DAVID EDWARDS
ROB MUZZY, RACE TUNER EXtraordinaire, is doing the talking. The subject is John Kocinski. More specifically, John Kocinski—up-and-coming GP great and an avowed non-fan of production-based racebikes—riding a Muzzy-prepped Yamaha FZR600 in last March's Daytona 600cc Supersport race. “He had apprehensions at first, sort of like, ‘This is just a g.d. streetbike and I'm just doing this because I have to,’ ” says Muzzy of the 21 -year-old rider who has dominated U.S. 250cc roadracing for the past two years, who humbled the Europeans at this year’s 250cc U.S. Grand Prix, who placed fifth in early July at the 500cc GP in Belgium—his debut race on the big bikes—and who was at Daytona on a street-based FZR only after much persuasion on the part of Yamaha, one of the companies that will foot the bill for Kocinski’s future GP career.
“But after practice, he came in with a smile on his face and a light in his eyes,” continues Muzzy. “After that, he had an, ‘All right, let's go’ attitude. He can say anything he wants about ‘streetbikes,’ but (at Daytona) he had fun.”
Kocinski’s Florida frivolity was no doubt helped by his decimation of the 600 supersport race, though he was saddled with a back-of-the-pack starting position after a questionable rules violation in his heat race. In the 10-lap race, Kocinski slashed his way through the pack and had the victory in his back pocket before the race was half over. It was an impressive performance.
That performance was even more impressive considering the rules governing AMA supersport racing; rules designed to put everyone on an equal basis. Engine modifications allowed are minimal: lmm-over pistons, a competition valve job, carburetor rejetting along with airbox elimination, and the addition of an aftermarket exhaust system. Chassis modifications are limited to the suspension, where aftermarket shocks and springs are permitted, and the brakes, where stainless-steel lines and accessory pads are allowed. Any type of DOTapproved tires may be used, though rims must remain standard.
Cycle World already had some experience in supersport racing by way of Associate Editor Doug Toland’s campaigning a Suzuki Katana 600 in club races and two supersport nationals in 1988. We had asked Rob Muzzy to modify the Katana’s engine for us. Muzzy, one of the mostknowledgeable engine men in American racing, has numerous successes in roadracing, flat-tracking, off-road racing and motocross to his tuning credit and now runs a performance shop. Muzzy’s Racing and Development (17216 Lilac St., Unit B-3, Hesperia, CA 92345; [619] 9495131). He did the basic engine upgrades allowed under supersport rules. The cylinder bores were enlarged to accept second-over pis-
tons and rings, the cylinder head was treated to a full-radius, racing valve job and Muzzy’s Supersport 4-into-l exhaust pipe was clamped into place; modifications that cost about $850, not including new pistons, rings and gaskets from Suzuki. At Muzzy’s recommendation, we added a carburetor re-jetting kit from Dynojet Research (200 Arden, Belgrade, MT 59714; [406] 399-4993).
We tackled chassis modifications next and followed a route that many supersport competitors take. Stiffer fork springs from Progressive Suspension (11129 G Ave., Hesperia, CA 92345; [619] 948-4012) firmed up the front end, a Twin Clicker shock from the Fox Factory (544 McGlincy Lane, Campbell, CA
95008; [408] 377-34220) took care of the rear, and grippy Dunlop K591 R’s were mounted.
After a few carb-jetting sessions, our Katana proved to a clean, strong runner with impeccably neutral handling, but it was still down on speed compared to the Honda Hurricane 600s that usually dominated the race results. Toland did win several club events, but could do no better than eighth in his two tries against national competition.
Things for Toland and other
Katana riders would g-et no better in 1989. Yamaha introduced its new FZR600, and to bolster its sagging performance image in 600-class production roadracing, announced a generous contingency program as well as the forming of a four-bike team that would contest Daytona’s 600 Supersport race. Rob Muzzy was hired to develop and prepare the bikes and, as noted, a reluctant John Kocinski would be the lead rider.
Honda added an interesting wrinkle to this year’s supersport campaign with its Canadian-model CBR600, a bike that was claimed to be eight horsepower more powerful than the stateside version. The AMA ruled that Canadian CBRs would be legal for supersport competition, though not many teams have made the effort to acquire the bikes, as—unlike Suzuki and Yamaha—Honda offers no prize money in U.S. racing.
Still, Cycle World wondered how the Canadian CBR and the new FZR would stack up our Katana, so we arranged for a comparison session at Willow Springs Raceway. Yamaha agreed to loan us Kocinski’s FZR600, straight from the Daytona victory podium. We procured a Canadian-spec CBR600 from Two Brothers Racing, a Southern California team made up of brothers Kevin and Craig Erion and ex-Bubba Shobert tuner Mike Velasco. The team had purchased the CBR from a Canadian dealer for about $6000 so that Kevin, 1988 Modified Pro Twins national champion, could get some four-cylinder racing experience. It should be noted here that no Kawasaki Ninja 600 was included because those bikes haven’t proved popular as race machines and no topline teams run them in national supersport races.
Close inspection of Kocinski’s FZR showed just how intensive race preparation for a front-running supersport bike needs to be. Not only did it have the prerequisite engine mods and suspension changes, but heavy-duty clutch springs and plates had been installed, a steering damper had been added, aluminum handlebars were fitted and all the stock plastic body pieces had been replaced by identical, but lighter-weight, fiberglass components.
For those interested in having a Kocinski-replica FZR, Muzzy Racing and Development offers a race kit that’s complete right down to the molded front numberplate, although Muzzy leaves the choice of rear shock and tires up to the owner (Kocinski's FZR used an Öhlins damper and Dunlop rubber). Those faint of wallet should know that opting for the full-house treatment will cost more than $2000, though that figure can be lowered by staying away from the $795 fiberglass bodywork kit and opting for Muzzy’s stainless-steel exhaust system, $150 less expensive than the $495 fullrace pipes, which use a lot of titanium.
The combined effect of Muzzy’s handiwork was evident at Willow Springs, where the FZR was a second a lap faster than the next-quickest supersport 600, despite being jetted for Daytona Beach rather than the thinner air of the California desert and despite having suspension rates calibrated for 130-pound John Kocinski rather than 155-pound Doug Toland.
The Cycle World Katana 600 was one full tick of the stopwatch behind the FZR, helped by a just-freshened top-end and by a suspension tailored over the 1988 season to Toland’s requirements. The Two Brothers CBR—in borrowed bodywork to replace its previously crash-damaged 1989 skin, hence the different look in this article’s action photography— was another second per lap in arrears. It should be pointed out, though, that except for a Kerker 4-into-l exhaust and a carb re-jetting kit, the CBR’s motor was as it came off the showroom floor, and while the suspension-beefed up with heavier fork springs and a Fox shock—felt fine, Toland wasn’t as comfortable pushing the CBR’s Michelin tires to the extent he did the more-familiar-tohim Dunlop K591Rs on the Suzuki and Yamaha. For the record, Toland felt a more-modified Canadian CBR would outrun our Katana, although it still would fall behind a properly jetted and set-up FZR.
Of course, that’s not to say that any one of these bikes in the hands of the right rider couldn't take the checkered flag on race day. But short of getting John Kocinski to guestride, our advice to those looking for the best chance of notching 600cc supersport victories would be to get an FZR600 and start making phone calls.
