2005 Kawasaki ZX-6R

You reach nearly 150 mph on the long back straight at Circuito de Almeria in southern Spain. That high-velocity beeline ends in an uphill, sixth-to-second-gear braking zone, followed by a 90-degree right-hander. When you're banging four quick downshifts and scrubbing big speed in such a short distance, you definitely appreciate the slipper clutch in Kawasaki's 2005-spec ZX-6R.

Huh? Kawasaki's stuffed a back-torque-limiting clutch in its 600-class streetbike? That's racer-replica territory, the type of Supersport hardware you'd find on Team Green's 599cc RR homologation-special, right? This year, though, it's the $8599 ZX-6R that has the meanest spec sheet on the middleweight block--and judging from a first ride, all the performance it needs to back it up.

After introducing the oversized 636cc ZX-6R in '03, Team Green has given the bike its first major makeover for '05. Consider the all-new black-anodized aluminum frame, packaging a slightly longer swingarm in a fractionally shorter wheelbase; Showa suspension (in place of Kayaba) for the first time on a Kawasaki middleweight; and dual-stage, oval-throat throttle bodies, a first on production motorcycles according to Kawasaki. Then admire the fashionable new underseat exhaust, weight-shaving petal discs and slick new bodywork. The '05 6R's parts book has more than 150 new numbers.A perfectly good reason, then, for the full-Monty press launch in normally sunny Spain. Make your own "the rain in Spain" jokes, but a downpour on the morning of the road ride served a useful purpose.

Gingerly feathering the controls on rain-slick roads provided a chance to appreciate the light clutch pull and progressive engagement.

Likewise, the new radial front brake master cylinder provides superb feel, and for once there's a rear brake that's not too strong. Good pedal feel makes it easy to use without inadvertent rear-wheel lock-up. And the Bridgestone BT014 tires provide excellent grip on cold, wet pavement.

Slippery roads force you to explore low-rpm throttle response, where the 6R's off-idle reaction is excellent and driveline lash is negligible. Acceleration is seamless from there. You can't feel the new shower-type upper injectors (mounted in the airbox) or the new servo-operated exhaust valve cut in at 5500 rpm.

As the twisty back roads dried, speeds increased, thanks in part to the Showa fork Kawasaki says is more compliant than its Kayaba predecessor. A year ago, most riders backed preload and rebound most of the way out, and the ride was still firm. According to Kiyohisha Yoshikawa, head of the ZX-6R's chassis development, the Kayaba's lightest spring and damping settings now fall in the middle of the Showa's adjustment range.

Moving to more mundane issues, the new underseat muffler occupies what was once useful storage space. That, and features such as a built-in lap timer, illustrate Kawasaki's intention to make the ZX-6R more track focused. Still, the new bars are closer to the seat than before, the saddle itself is lower and the footpegs feel relatively low as well. You'll find practical touches such as lockable hangers for two helmets, bungee hooks and a passenger seat that seems reasonable enough. (We won't say who needed a two-up ride in from the gravel trap, but his initials are M.G. --Ed.)

Besides the major induction and exhaust changes, engine tweaks include 1mm-larger valves, reprofiled cams and a deeper sump to reduce internal drag. While Yukikazu Sumitomo, who headed up the engine project, was coy about dyno figures, we can tell you the midrange doesn't disappoint. The 636cc powerplant pulls hard from 8500 rpm. At the top end both a significantly higher power peak and a longer overrun help make shifting seem almost optional.

All that power demands excellent brakes, and the ZX-6R delivers, with progressive initial action, ferocious bite and great feedback. The 1⁄5-turn throttle makes it easy to match revs on downshifts, and the slipper clutch kicks in to correct minor errors, virtually eliminating rear-wheel hop.

One of the chassis team's goals was increased stability, and you can feel it when it comes time to initiate turns at track speeds. This bike is a claimed 6.6 pounds heavier than last year's ZX-6R, making it the heaviest of the current middleweights. The underseat exhaust contributes to most of that additional heft. Engine castings are also thicker and heavier to handle the increased power, while the slipper clutch adds weight, too. That said, the wheels and tires are lighter than before, as are a host of other components.We rode our final sessions on Bridgestone's latest 002 race tires, and the stock suspension can easily handle stickier rubber, at least at Almeria, which is smoother than the average U.S. track. While the 599cc ZX-6RR has a mounting boss for a steering damper, the R has neither one nor seems to need it.

Honda's CBR600RR, Kawasaki's ZX-6RR, Suzuki's GSX-R600, and Yamaha's YZF-R6 all remain Supersport-legal, though Team Green will build only enough RRs to meet homologation requirements. The fight between those bikes and supersized middleweights such as Triumph's Daytona 650 and--especially--this new ZX-6R is sure to be a brawl.For a month or two you can only speculate. But remember the old streetfighting maxim: A good big man will always beat a good small man. We'll see if that applies to motorcycles as well.