This article was originally published in the April 1997 issue of Sport Rider.
In the dog-eat-dog world of Superbike racing, gaining a competitive edge over your rivals means taking advantage of every loophole in the rules you can find. So many factories use the homologation rule (to be eligible for Superbike racing, a bike must be produced in a specified number of street-legal examples for sale to the public) to build a limited number of bikes that include features not found on their standard, mass-produced models. Like Kawasaki and its ZX-7RR.
Just what do you get for a bike that costs nearly $3000 more than the standard ZX-7R? For starters, you get a set of 41mm Keihin flat-slide carbs to replace the standard 38mm constant-velocity mixers. Both AMA and World Superbike rules specify that stock carbs must be used, so Kawasaki ensured its racer would have sufficient breathing capacity once the other go-fast goodies were installed. These fully adjustable state-of-the-art carbs give racers the tuning latitude necessary for all-out performance.
Other subtle engine differences include a heavier crankshaft flywheel (a trick gleaned from the Muzzys superbike effort) that helps get power to the ground, while a close-ratio tranny enables you to keep the high-strung in-line four on the pipe. Features like involute splines on the cam chain sprocket ease race-weekend maintenance.
Of course, getting around corners is just as important as added horsepower, so Kawasaki included some tricks in the 7RR’s chassis as well. For instance, although externally similar to the standard 7R’s components, the 7RR’s 43mm inverted fork offers 13-way rebound and 28-way compression damping adjustability (versus the standard 7R’s 12-way rebound and eight-way compression damping settings). And the 7RR’s rear shock offers an additional 14 steps of rebound adjustment over the standard model’s four-way settings. In the front-brake department, Nissin race-spec, six-piston calipers sport three-way staggered piston sizes and grippier brake pads.
The 7RR’s frame geometry is variable as well. An adjustable swingarm pivot allows you to set the rear suspension for maximum traction, while eccentric bearing races in the steering head allow alterations in rake and trail dimensions for differing riding styles and tracks. Weight-saving measures like an aluminum rear subframe cut poundage, although various junctures on the chassis have been beefed up for increased rigidity. Do all these features add up to a better ZX-7? On the racetrack, the same unflappable stability exhibited by the standard 7R is present on the RR, only the added suspension adjustability allows you to get the handling dialed in that much better (we never touched the swingarm pivot and steering head; overall handling was just fine). Acceleration felt stronger than the standard 7R, and the close-ratio gearbox allows you to keep things on the boil in the tight stuff. Top-end felt the same, though, which is probably due to the stock muffler choking things up on the exhaust side. The 7RR’s higher-spec front brakes gave slightly better power and feel, along with improved fade resistance.
On the street, however, the 7RR’s flat-slide carbs struggle to run cleanly at low rpm, making slow going a laborious affair. Stoplights require a bit of throttle/clutch juggling to get away smartly, and the close-ratio tranny’s tall first gear only exacerbates the problem.
Of course, the ZX-7RR was meant to be a track weapon anyways, so these gripes are trivial; components like the stock exhaust will be jettisoned for race-spec pieces before it even hits the tarmac. And the finished product can be quite impressive—just ask Rob Muzzy or Doug Chandler. —K.K.
|Suggested Retail Price:||$11,999|
|Engine type:||Liquid-cooled, transverse in-line, 4-stroke four|
|Bore x stroke:||73.0 x 44.7mm|
|Carburetion:||4, 41mm Keihin flat-slide semi-downdraft|
|Rake/trail:||(Adjustable) 25 deg./ 3.9 in. (99mm)|
|Wheelbase:||55.9 in. (1420mm)|
|Dry weight:||441 lb|