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RACE WATCH
The balance of Superbike power
In both AMA and World Superbike racing, Twins get 1000cc displacement, Triples get 900 and Fours get 750. In the 14-year history of WSB, Twins have won all but four titles, causing people now to call the series “Battle of the Twins.” Here in the U.S., Honda’s RC51 Twin has a clear power advantage even if it can’t always apply it. Pressure groups are lobbying the FIM and AMA, calling for change.
On the world scene, the MSMA (Motorsport Manufacturer’s Association) has veto power over any decision the FIM may make on this issue. I called WSB tech inspector Steve Whitelock for some insight.
“They’re all (MSMA members) in a funny zone, coming up with some insane ideas. Honda doesn’t want to lose any advantage it now has. Yamaha would like Supers to go straight to lOOOcc four-cylinders.”
Under a straight lOOOcc rule, power would be equalized (“indexed”) by limiting four-cylinder bikes to minor Supersport-style modifications, while Twins would continue at full-race level. Yamaha might like a 1 OOOcc rule because once its YZR-M1 four-stroke Grand Prix bike takes to the track, the company will make a streetbike spinoff version.
Making a 750cc Four accelerate as hard as the Twins is extremely expensive, so Suzuki’s budget would go farther in WSB under a lOOOcc rule. Whitelock went on to say that Harald Eckl, who runs Kawasaki’s WSB team, speculated that using a longer-stroke crank from earlier ZX-7s bumps the current engine to 817cc, and so would be a practical way to boost acceleration. A kit might be put together for about $5000-a lot less than the $10-17 million Honda reportedly spent in winning WSB that one time with its RC45 V-Four. Others suggest that, with the new Suzuki-Kawasaki business alliance, Suzuki may abandon WSB to concentrate on the new fourstroke GP class, while Kawasaki would remain in WSB and not contest GPs. A straight lOOOcc now? In three years? Or give the Fours 10 percent now and see how it goes? How about restrictors or rev-limiters?
Merrill Vanderslice, the AMA’s Director of Pro Competition, referred to a coming “infinite series of meetings” between the MSMA and the FIM.
“We’re going to do something,” he said, referring to U.S. rumblings that at least one maker would welcome a displacement change as an alternative to leaving AMA Superbike.
How were 1000 and 750cc chosen to begin with? The idea was to allow both engine types to pump the same amount of air and so make the same power. Crudely, airflow is displacement times rpm. Piston speed was thought to be what limited max rpm, keeping Twins with longer strokes (and thus higher piston speed) to lower peak revs, while letting Fours peak higher. Therefore, their ratio of displacements should be the inverse of their ratio of stroke lengths. Ducatis, with a 66mm stroke, raced against Fours with strokes of 48-52mm, so the 1000/750 ratio looked right.
Trouble is, piston speed isn’t what actually limits engine rpm. Oil will happily lubricate pistons as fast as you care to drive them. The real limit to performance is how hard everything gets yanked as pistons stop and start at the ends of their strokes-piston acceleration. If we set some high number such as 7000 g as today’s “caution level” in piston acceleration, and calculate peak rpm from that, we get 14,700 rpm for Fours and 12,450 rpm for Twins. The ratio of these numbers gives us lOOOcc Twins and 847cc Fours. As it happens, 825-850cc is being proposed as the new limit for Fours, with Triples notionally to receive 955cc. Whether this proposal will be adopted, postponed or replaced remains to be argued.
The Twins are admirable-developed to run reliably at revs as high as 13,200but 10 out of 14 titles is a lot of asymmetry. Time for change?
Kevin Cameron
Will Davis, 1964-2001
The sentiment from those who knew him was clear: This isn’t supposed to happen to guys like Will Davis. The 36year-old AMA Grand National veteran and five-time Motorcycle Asphalt Racing Series champ died as the result of > injuries sustained in a multi-rider crash during the first lap of the Grand National final in Sedalia, Missouri, August 25.
It was Davis’ 18th season of GNC racing, during which time he’d amassed 32 victories and finished second in the championship twice, in the 1997 and 2000 seasons. He was seventh on the all-time GNC win list, and was third in the series standings entering the Sedalia round.
The North Carolinian’s off-track accomplishments were also to be lauded, Davis active in charitable work with terminally ill children. The AMA recognized his giving nature in this regard by bestowing upon him the AMA Professional Sportsman of the Year award in 2000.
Davis is survived by his wife, Rhonda, and 7-year-old son, Cole. Two funds have been established on behalf of the Davis family: The Will Davis Memorial Fund, c/o Wachovia Bank, 301 E. Ash St., Goldsboro, NC 27533; and The Will Davis Family Trust Fund, c/o AMA Pro Racing, 13515 Yarmouth Dr., Pickerington, OH 43147.
Mark Hoyer
Baja Aragon
Got Baja? Well, it seems the Spanish do, so factory Honda desert racer Johnny Campbell and I hopped a plane to find out about “Baja Aragon,” a one-day, 500-mile dash around central Spain.
We borrowed a couple of Honda XR650s from Boluda Honda in Castellón, added big tanks, race suspension and Pro Circuit mufflers, then headed to the hills for some training runs. And let me tell you, the mountains just inland 'from the south coast of Spain offer some sacred riding-no wonder many of Europe’s off-road aces practice here.
The hills gave us some idea of the ground conditions, but the race was run near Zaragosa, where it’s mostly flat. The course consisted of a 250-mile loop, run twice. Just as in our Baja races, bikes and cars compete, but here
the cars are more like FIA rally racers, and for good reason. The course is much smoother then in Mexico, made up mostly of dirt roads connecting farm fields. No open desert running.
Anyway, it was a lot of fun that lasted way too long. The twisty roads all blurred together and the pace of lead locals Isidre Esteve and Nani Roma was scorching. I couldn’t stay on the course going these speeds. Neither could Campbell, though he fared better than I did. Esteve won the event for the second year in a row on his KTM 520, with Roma second some 14 minutes back. Another local, Jose Luis Steuri, took third on a Honda, beating out Campbell by just a few minutes. I was a distant fifth, some 45 minutes behind the leader, whelping about sore wrists or something. No booby-traps, no cars coming backward on the course and happy fans everywhere, Baja could learn from the Baja Aragon.
Jimmy Lewis
