2003 Kawasaki ZX-6R Quick Ride

Quick Ride

It's nightime and the sight of headlights pointing skyward is a sure-fire tip to the Johnny Law that someone's not following the rules of the road. In preparation for a full-throttle blast, I crouch forward in what becomes a vain attempt to keep the front wheel on the ground.

I get on it, hard, and the front end inexorably rises toward my face as the tach hits 10 grand. There's still 5500 rpm of playtime left in the powerband, but I have to roll off slightly to keep from flipping over backward. The front wheel stops its rising elevation as it hovers just above the tarmac at three-quarter throttle.

With the crankshaft spinning 250 times each second, the yellow shift light signals that it's time for the next gear. A quick click of the buttery gearbox, a forceful twist of the wrist, and the front end soars skyward again.

This is no ordinary 600.

Indeed, the new Kawasaki ZX-6R isn't a 600 at all. While other manufacturers build middleweight sportbikes to fit Supersport regulations, the brain trust at Kawasaki figured a street rider has no such limitations. An extra 37cc may not sound like much, but the new 636cc Kwacker provides a dose of power that will likely surpass the other contenders in the class.

For Supersport racing, Kawasaki offers its ZX-6RR, a 599cc machine with racing elements previously unheard of in the 600 class. For the extra $400 over the single-R's low $7999 price, the double-R has an adjustable swingarm pivot, a slipper clutch, forged instead of cast pistons, a different bore/stroke ratio and a boss welded on the frame for easy fitment of a steering damper. Check out what Tommy Hayden had to say about the new Ninjas in his interview with Kevin Duke.

Those who ride on the street instead of the racetrack, which is probably about 95% of all riders, will come to love the ZX-6R. Even at the same price as last year, the regular Six-ar comes with a list of trick bits that its competitors can't match.

Last year's ZX-6R was a terrific, well-rounded street motorcycle, with relatively comfy ergos and a punchy engine. What it didn't have was class-leading performance on a racetrack.

Well, that's all old news now, as I found out aboard the new ZX-6R on one of its first street rides in the U.S. The new ZX is about as closely related to the old one as you are to Michael Jackson's chimp, or for that matter, Jacko himself. The handlebars stick out from under the top triple clamp instead of above, and the windscreen seems like it was left in the dryer a bit too long. Shrunk, too, is the instrument cluster, down from two large analog dials to one small dish at the center that incorporates a digital speedo surrounded by a circular LCD bar graph. Underneath sits the runner for the ram-air intake, centrally fed from the nose directly through the steering head like Honda's RC51.

That pressurized air gets sucked into the engine with a new fuel-injection system. Kawasaki uses a dual-butterfly arrangement in the four 38mm throttle bodies, as is becoming the norm in the industry. To counter abruptness when coming back on the throttle, the ZX-6R uses a lower butterfly to control the intake at lower throttle applications and reduced intake velocities. A butterfly in the upper end is actuated during big throttle openings. A higher-powered 32-bit ECU keeps tabs on the engine via, among many inputs, double the number of triggers on the flywheel.

The crankcase is lighter and more rigid than previous, and its more compact dimensions allowed engineers to play with engine location and swingarm length. Valve diameters are the same large sizes as last year (27.0mm/22.6mm) but a 10mm shorter cylinder head allows their lengths to be shortened the same amount. This reduces mass and, along with lighter tappets and valve springs, the new mill can squeeze out 15,500 rpm before the rev limiter cuts in to spoil the frantic party. New cam profiles supply the necessary guidance to control the lightened valvetrain at these lofty levels.

Okay, we've torn apart the engine and you didn't even get grease under our nails. Whaddaya say we bolt this puppy together and find out how it rides?

Upon first swing of leg, the compactness of the new ZX is apparent the thing feels tiny. There is an amazingly short stretch from the seat to the bars, so the sportbike hunch is not so radical even with the new forged-aluminum bars mounted below the triple clamps. For maximum comfort and front-end traction, a rider wants to sit as close to the front as possible, but this has inherent danger: Nads get tenderized when sitting against the tank over bumpy roads. If your wife is ovulating and you're trying to bring another little bike nut (yeah, there's a pun there) into the world, use caution.

The new injection system means cold starts are a one-button process no fuel-richener lever fiddling. Throttle response is excellent, and it revs up sweetly, almost liquid-smooth. Well, if it's like liquid, it's carbonated because there's no provisions to damp out vibration. The tank, bars and pegs are much more alive than with last year's glassy engine.

The cable clutch is easy to modulate, making for easy getaways. The ZX feels like it's geared short, but the lower two gears have the same ratios as last year. Gears three through six are closer spaced for better acceleration on the track. The transmission has a new shift-cam shape, lever ratio and return spring (if a lighter spring is desired, Kawasaki offers one as an optional part). The result of these tweaks is a slick gearbox, as is typical of recent Kawis. Strangely, neutral was difficult to access from first gear, making one wonder if Kawasaki's ubiquitous neutral-finder system has been yarded from the new bike; the Green guys are checking for us.

With the shorter gearing of the top gears, an 80-mph cruise in sixth results in the engine turning 7000 rpm. While that may sound quite high, consider that's not even halfway to the screaming redline. Compared to other 600s, the big-inch (big-cent?) ZX has a wider powerband, though the search for serious power begins north of the 9000-rpm mark. Power tapers off after 13,000 rpm, but there's still useful over-rev up top. Bottom-end urge is a little less than expected, but with cams designed to work with the stratospheric rpm up top it's understandable. At WOT the intake noise of the ZX's ram-air dominates, building from a guttural howl to an R6-like shriek up top. It's spine-tingling music.

Keeping tabs on the quickly escalating revs is a small LCD bar-graph tach that circulates around the digital speedo. But the Cyclops-ish instruments are pointed too far horizontal to see the teeny display. Thankfully, Kawasaki has fitted a shift-indicator lamp that is easily seen and is adjustable in 250-rpm increments. The gauge pack also includes a clock, tripmeter and temperature gauge, along with a stopwatch that records up to 99 laps of your trip down to 7-11. Conveniently, the instrument lighting can be adjusted to one of three levels of brightness.

This is all good, but it doesn't mean a whit if the new ZX can't go around corners as good as the competition. We're happy to report the red (or blue or silver or black) machine ranks up there with the best backroad scalpels we've ever tested.

One of the best ways to build a sweet-handling chassis is to reduce weight. At a claimed 355 pounds dry, the new ZX would be 22 pounds lighter than before. If so, that would mean a true tank-empty weight of 384 pounds. We'll give you the scoop once we get a chance to throw the 6R on our certified scales. Magnesium engine covers, lighter brakes, a detachable aluminum subframe, and the internally-reinforced aluminum swingarm (that is slightly longer this year) kick mass.

The steep 23.5-degree rake of the previous model has been kicked out to a more moderate 24.5 degree angle via a revised triple-clamp offset. This loss of steering quickness is countered by a short 95mm of trail (3.77 inches), ball-type steering head bearings and the lighter front brakes. Directional changes are quick but not too much so, and a generous amount of stability helps generate serious lean angles. Tying the new aluminum frame together for added chassis rigidity is a new engine mount on the front side of the head as opposed to the rear as previous.

There is plenty of ground clearance available, as I was only able to graze the short hero blobs when corner speeds were dipping the turn signals within inches of the ground below. Pegs are high but not very rear-set, so even though there's not a lot of legroom knees don't get too cramped. The Bridgestone BT012s fitted to our test bike offered loads of grip and plenty of feedback. Nice buns.

Helping corner-carving competence is the nicely-mannered fuel-injection. Some less-refined injection systems have a chassis-upsetting abruptness when coming back on throttle, but this annoying trait has been exorcised by the dual-butterfly arrangement on the ZX. The best compliment I can give a fuel-injection system is if it feels just like a well-tuned set of carbs, and with the ZX it didn't cross my mind that it doesn't have the old-school mixers until halfway through the day.

Holding up the wheels of the Zixxer is a completely new Kayaba suspension package. Up front, a 41mm inverted cartridge fork signals the arrival of rigid upside-downers to the 600 class. Along with stiffer fork springs for better control at a race pace, the new fork includes top-out springs. Kawi says they help keep the front tire in contact with the tarmac under hard acceleration by reducing the speed of the upstroke. The new shock has a stepless damping adjuster with check valve instead of needle valve for improved damping. It, too, has a top-out spring that is designed to keep the back tire on the pavement through large bumps and under heavy braking. We were impressed by the new suspension. Even with more preload than my scrawny brawn requires, the ride quality isn't too harsh, showing good control of high-speed damping.

The trickest bits to hit the sportbike scene lately are radial-mount calipers, and the moderately-priced ZX joins the fashionable club that has just Aprilia's RSV Mille R and Suzuki GSX-R1000 as members. These brakes are stellar, offering big power but with excellent modulation. The more rigid design sends more consistent and positive feedback through the lever, and the individual brake pad for each of the 32mm pistons keeps pad wear evenly distributed. Friction-reducing sealant on those pistons is said to also improve brake feel. And, at 0.5 pound lighter than the previous 6-piston calipers, the new binders lop off a full pound of unsprung weight from the front end.

With better calipers, Kawasaki engineers figured tiny-looking 280mm rotors would suffice. With 20mm diameter less, the rotors were given a rather beefy 6mm of thickness to help dissipate the heat. At press time, Kawasaki was unable to confirm whether the smaller but thicker discs are lighter, but we expect to have an answer soon.

Fit and finish is a good as anything we've seen from Kawasaki. The cockpit is very tidy, with plastic shrouds that covers the electrics and ancillary bits that can spoil the appearance of lesser machines. The nifty, flush-mounted taillight cluster has 21 LED bulbs that are said to last 3000 hours, compared to the 500 hours that are typical of a filament bulb. The pillion pad is easily detachable and can be replaced with the snazzy seat cowl that is included in the ZX's low $7999 price tag. The rear hugger fender completes the attractive rear end. Tighter packaging has resulted in a miniscule underseat storage compartment.

So what have Kawi engineers wrought with the new ZX-6R? Fans of the old ZX would bemoan its buzziness, its relative lack of comfort, and the stripping of what was once the torquiest mill in the middleweight class.

But the 600 class has gradually become less of an entry-level market and continually leans more toward a cutting-edge sportbike that can rip around a racetrack unlike anything short of a 250cc GP bike.

In this context, the new ZX-6R handily stomps every other middleweight previously built. It has heaps of power (we're guessing more than 100 hp at the rear wheel), top-shelf suspension and brakes, and corner-shredding handling. And there's even decent wind protection from the diminutive windscreen to go along with its attractive and well-finished appearance. Combine this superb performance with the widest selection of colors and a price that can't be beat in the class, and Kawasaki's got a winner in its showrooms. We'll be sampling the new offerings from Yamaha and Honda in the next couple of weeks, so stay tuned to see how the Kwacker stands up in relation to the new-for-'03 challengers.

The bottom line: If you've already ordered the new ZX, you're going to have one of the best mass-production sporting tools we've tested. Just keep your old one for sport-touring duty.