Back in 2002, Kawasaki dropped a bomb on the 600cc class: it punched out a 600 motor an extra 6%, creating a 636cc middleweight. It was the equivalent of an overweight fighter convincing a rival to compete at a catch weight, instead of dieting to make the existing class weight.
36cc may not sound like much -- it's the displacement of a weed-whacker. But it made a difference; in the closely-fought supersports class, the 636cc Kawasaki soon topped Sport Rider's comparison test.
Street riders loved the extra bottom and mid-range, and didn't give a rat's ass whether or not the machine could be homologated for road racing. Kawasaki wanted to go supersports racing around the world, however, so it also built a sufficient number of (destroked, IIRC) 599cc ZX-6RR versions. That bike was perfectly nice -- I endurance-raced it in the AFM's season-ending four-hour at Infineon, and it was a damn sight faster than I was -- but it was not measurably better than rival OEM's 600s.
When we heard that the 636cc displacement was being resurrected this model year, most sport bike riders were happy, and so what if it couldn't be raced?
In fact, Kawasaki again released enough 599cc versions for a '600' to be homologated to race in the Japanese domestic championship. I figured, what the hell, even if Kawasaki doesn't bring the 599cc homologation version to the U.S., most of the people buying the new 636 won’t be racing at the national level, and club racers will have opportunities to race it in any number of 750 classes. The original 636 was actually pretty competitive when the AMA still had a 750 Superstock class (Tommy Hayden won on it -- at Daytona of all places -- in 2003.)
I have to say, however, that I was surprised when AMA Pro Racing announced that the full-on 636cc version would be eligible for the SuperSport and Daytona SportBike classes in 2013. Of course, DSB isn't strictly a 600cc class; the Triumph 675cc triple, and Ducati's 848cc twin are homologated.
Still, the extra displacement in a four seemed a little unfair to Suzuki, Yamaha, and Honda. I emailed a friend who prepared a privateer DSB a few years back, and asked him what he thought. He pointed out that, nominally, the Kawasaki had to compete at a higher minimum weight -- 375# to the nominal class weight of 355#. But, my friend felt that few DSB-class bikes were actually at the 355 limit; most are probably running close to the Kawasaki's 'penalized' weight of 375 anyway.
Higher minimum weights are not necessarily practical ways to level the racetrack for everyone. When Danny Eslick and his 1125cc Buell attracted the ire of 600cc competitors in DSB, the AMA responded to non-Buell teams' howls by raising the Buell's homologated weight. The thing is, even the raised weight was less than most Buell race bikes' actual weight. I.E., the penalty occurred on paper only, not on the asphalt. And, even when raised limits result in raised weights on the track, the penalizing effect of ballast is moderated when ballasting becomes another tuning parameter.
AMA Pro seems to think that they can do this, and Kawasaki will come back with a team. But it's the kind of thing that weakens the resolve of other entrants. Are displacement limits really limits? Or are they just suggestions?
Don't get me wrong; I loved the old 636, and I'm sure I'd love the new one, too. And I think it should be raced... in, for example, the AFM's 601-750cc Production class.
In fact, if I was Suzuki, I'd immediately ask to homologate the GSX-R750 in AMA Pro's SuperSport and DSB classes. Now that's a kick-ass middleweight.UPDATE As Sport Rider's Kent Kunitsugu points out, major teams in the affected classes would have been informed of the rule before it was made public, so my statement that the announcement comes too late to be effectively protested is not necessarily true. And the other manufacturers do(?) have input on rules. So maybe I flew off the handle a bit... That said, I maintain that if the ZX-6R starts winning, Honda, Suzuki, and Yamaha riders will start whining.