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2004 Kawasaki ZX-10R Track Test: Part Two

After our “teaser” Part One, Willy caught his breath and gave us all the details. Here they are:

Christmas came early for me this year. When Dirck asked if I could cover the world introduction of the new and much-anticipated ZX-10R at Homestead Raceway in Miami, Florida, I tried to remain cool, but couldn’t contain myself, answering “YES!!” before he could finish asking the question.

This is an important model for Kawasaki and is a milestone for the company in a couple of ways. One, the introduction of the 10R comes on the 20th anniversary of the original 1984 ZX900 Ninja, a landmark motorcycle that set the sportbike world on its ear with its light weight and high horsepower in a compact package. Two, the 10R marks the return of Kawasaki to the liter class with a motorcycle to go head-to-head with the 2004 class competitors, since the venerable ZX-9R had been relegated to the sport-touring segment several years ago by the likes of the current Yamaha, Honda and Suzuki open-class sportbikes. Claims of class-leading horsepower with 600-class weight and dimensions made me anxious to see if the new ZX was the real deal, or just hype.

Until I was able to actually ride the bike, I could only look at the press material. In the sales brochure, there was also information about the ZX-6R / 6RR. With Kawasaki making bold claims about its liter bike being the size and weight of a 600, I couldn’t help making the comparisons between the 10R and the ZX-6R in those areas to see if, at least on paper, their proclamations held up under scrutiny. Read on. Rake and trail are 24 deg. / 102mm for the 10R, 24.5mm / 95mm for the 6R. Wheelbase is set at 1385mm (54.53″) for the 10R, 1400mm (55.12″) for the 6R. Claimed dry weight of the 10R is 375 lbs., and the 6R weighs in at 355 lbs. Ahh, that’s enough to get the salivary glands going, eh?

Kawasaki describes the 10R as an expression of what it calls “Ultimate Supersport!” Statements like “best power-to-weight ratio in its class”, “race-oriented performance” and “aggressive styling” were all used to both design the new flagship and to let the world know that this bike is all business. Indeed, it is. I’m a gear-head almost to a fault (some would take out the ‘almost’ part) and would be happy to chatter endlessly about valves, clutches, fuel injection, etc., but since we already posted the specs of the new 10R issued by Kawasaki, I won’t rehash all of them here, but will cover the details not mentioned in that release. So let’s ride, shall we?

Kawasaki chose to introduce the new ZX at Homestead raceway, which has a Fontana-like layout. It has a shorter front straight than Fontana, and leading up to it is a slow exit from a quick right-left set of esses, instead of Fontana’s much faster, open sweeping left onto the banking. Interior straights are almost as long and are (with the exception of turn one entering the infield) connected by second-gear corners. This track puts a premium on a motorcycle’s ability to build and scrub speed, and opens the door many times to enter highside city. The relatively short straights of the outer oval and infield section meant that the last two of the six transmission ratios would go unused. Still, the top of fourth gear would have 157 mph registering on the display.

With Florida weather being anything but constant, or predictable, the possibility of rain would always be in the back of my mind. Testing this new missile in the rain was not a particularly pleasant thought; though only because it would severely limit the availability of the bike’s resources to the rider. Thankfully, the weather remained dry – for the first day.

Walking up to the 10R, you can’t help but notice how small it is. You blink, re-focus your eyes to make sure you got the right look the first time, and wonder if indeed, this is a liter-class motorcycle, or a middleweight with a sticker job. Swing a leg over, and you feel how small the 10R is. Frontal area is minimal, and you’ll quickly figure out that the only way to get any wind protection from the fairing will be to get into a racer’s crouch. The concave shape of the top of the gas tank does its part to make this possible.

Turn the key and watch the instrument display cycle through its self-diagnostics, then thumb the starter button. With the engine running, you finally are convinced that this is the big bike. Although somewhat muted, the sound of the bike gives it a powerful presence. Blipping the light-action throttle, you hear how quickly the revs rise and fall.

Selecting first gear and feeding out the clutch, the bike rolls out of the pits on the smallest opening of the throttle, despite a tall first gear ratio that is good for 80mph or so. The first few laps are sighting laps following behind the Kawasaki test rider, whom I am directly behind, so I take this time to pay attention to things like engine vibration, ergonomics, etc. Climbing steadily through the rpm range, the engine is remarkably vibration free, despite not being fitted with a counter balancer. The compactness of the motorcycle does not translate to a cramped riding position, although the footpegs may be a tad on the high side. The reach to the low(ish) handlebars is short and their angle feels natural. There is no doubt what the intentions of this bike are, but it does not exact a high penalty in rider comfort. Kawasaki says ergonomics for this motorcycle are the result of both computer simulations and extensive rider feedback. I feel like I have wide latitude in seating positions, despite the 10R’s small dimensions.

As the test rider increased the pace, I diverted more attention to maintaining the proper line, rather than the niceties of the motorcycle. Because of the prodigious amounts of torque available down in the midrange, I am free to look ahead to match the lines of the test rider and figure out braking points without having to give any thought to gear selection, or rpm reading, This is a good thing, since the ZX-6R-style tachometer bar graph readout is as difficult to read on the 10R as it is on other Kawasaki models you find it on. The programmable shift light – and rev limiter – both serve as shift indicators, since the engine does not sound or feel as if it is revving as high as it actually is. This engine loves to rev, just like its middleweight brothers, but has the luxury of calling on the midrange for very rapid acceleration.

After 3 or so laps, the test rider signals for us to continue while he enters the pits, just before the esses leading to the front straight. Exiting the tight left-hander, I twist the throttle to the stop, letting the rpms rise to redline in each gear, and I am rewarded with a seamless, arm-stretching acceleration like I have not experienced before. This thing absolutely rips! The front straight is but a brief memory, and you’re left wondering if you used a shortcut to arrive at the first turn.

Unfamiliarity with both the track and the ZX meant that the first couple of sessions were spent figuring out the proper line for a fast (kind of) lap, during which time the 10R’s ease of use quickly highlighted itself. While I was doing connect-the-dots through the corners, the quick, but stable steering accommodated mid-corner direction changes without fuss. Suspension felt firm, but not unforgiving. Clearly, settings were chosen for track duty. If I approached a corner too fast, the brakes bailed me out. Conversely, if I scrubbed too much speed entering a corner I could simply open the throttle and use the basement-level torque to pull me up into the serious horsepower.

After a couple sessions of following others who were more familiar with Homestead than I, and becoming more intimate with the ZX’s capabilities my pace increased dramatically. Brakes made the straights longer because I could use their massive power and exemplary feel to wait until the last moment to throw out the anchors. The new “petal discs”, combined with the four-pad, radial mount calipers, practically give the rider a do-not-go-to-the gravel trap stopping capability. Tons of power can be accessed with one or two fingers, with loads of feel. Initial bite is not as high as some other setups, and this is a good thing because it allows the rider to get weight smoothly transferred to the front wheel so that the rest of the formidable stopping power can be called upon. Throughout the day, there were times that I was carrying the rear wheel off the asphalt, but didn’t realize it until I eased off the brake to start the turn in and the rear wheel swung out slightly! Braking feel remained consistent and fade-free throughout the day, no matter which of the 14 of the press bikes I was on. These are the best brakes I’ve sampled so far, bar none. Awesome.

The engine is directly responsible for me finding out how good the brakes are. It generates thrust that’s probably on par with the space shuttle, and the stepless powerband invites you to open the throttle a little sooner every time. Whenever exiting a corner, the engine’s ability to rip through the gears and quickly generate the big numbers never failed to amaze me. The way the engine gathers revs while feeding on a high-velocity diet of air and fuel must be experienced. Lots of time spent at 8,000 rpm and above caused me to think the motor felt peaky. Roll on acceleration in second and third gears from 3,000 rpm puts and end to such speculation as the engine pulls authoritatively from the basement to the peak of the rpm range without even the smallest step or hit.

Claims of more than 180 horsepower with ram-air don’t seem far-fetched in my mind. In the first couple of sessions, I was using my hands and arms to hang on under acceleration. My arms would pump up and hands would go numb. I quickly learned to grip the tank with my legs, which took care of that issue. Also, if the rider position is not forward over the gas tank in the first three gears, perhaps four, the front wheel will soon be airborne.

The transmission on the first morning was a reluctant participant, requiring two, sometimes three attempts to slot the next ratio into play when the pace got quick and less attention was paid to shifting technique. In the afternoon, the bikes were much better, but would still throw a small tantrum once in a while. The bike I rode in the first session on the first day shifted almost perfectly in the first session on the second day. Perhaps, mileage was all it needed, but a change mid-day (on day one) to a larger diameter rod in the shift linkage may have played a part as well. I know I adjusted my technique to deal with the quick throttle response and light flywheel as well. After that, all was well with gear changes.

The slipper clutch also played a large part in fast and smooth corner entries. Adjustable for a rider’s preference, it allows the rider to quickly feed out the clutch after banging a few downshifts without causing the rear wheel to hop and chatter. Deliberate attempts to cause rear wheel hop were futile, and all that indicated the slipper clutch was doing its job was a little pulsing at the clutch lever.

Opening the throttle at high lean angles with this much power on tap is a major concern for the rider. Happily, throttle response and control from the fuel injection is extremely good, being immediate – but not abrupt. A second throttle valve in the 43mm throttle body is controlled by the ECU, which works in concert with the exhaust butterfly valve in the titanium collector and assures smooth, strong acceleration. Instead of dual sets of injectors, Kawasaki has developed automotive style injectors that spray a mist of fuel comprised of droplets about 70 microns in size, versus a typical droplet size of 120 microns. The finer mist assists throttle response, power and emissions. Opening the throttle while leaned way over, or adjusting speed mid-corner on part throttle did not reveal any glitches that I could discern, which is very good news. . In one instance, where I was opening the throttle in fourth gear at the exit of the second part of a fast right-hander, the rear wheel spun up. With a small adjustment to the throttle, the slide was controlled and the rear end came smoothly back in line. That’s big power, and great fuel injection!

Suspension front and rear was very well behaved while going for fast lap after fast lap, maintaining consistent, and fade-free damping. The Kayaba units have spring and damping setups from the factory that favor track duty, which is in keeping with this bike’s mission. Still, the settings initially sampled while I got faster showed the suspension to be plush but well controlled. Top out springs fitted to the forks and shock help control suspension extension, and in turn help control chassis pitch during the transition from acceleration to braking and vice-versa. A Diamond Like Coating (DLC) is applied to the lower fork tubes to reduce stiction and make the surface more durable. The rear shock works through an all-aluminum suspension linkage, and is placed left of center, to allow tucking in the exhaust system, increasing ground clearance.

Fast sessions in the afternoon had the bike moving around a bit too long after a bump. Coming in for a rebound damping adjustment in the rear to slow the rebound made me realize that more would be better, and that the front would benefit as well. After all the clicking and turning was done, a ZX that maintained precise, unruffled lines over the bumps showed itself, even while braking to the apex, or crossing a sizeable transition from the back straight into the infield. The right-left flick of the esses, and the left-right transition of turns three and four highlighted the stable, yet flickable (middleweight flickable) nature of the 10R. That was accomplished with just a couple of relatively small damping adjustments. Pretty impressive for a street bike.

Ground clearance was never an issue. I only occasionally dragged the left peg when coming off the back straight into the infield. That would have been easily cured with a little more preload to deal with my slightly larger girth, but rain on the second day put an end to the experimentation. (Suspension settings are provided at the end of the article.)

Reducing unsprung weight is an ongoing process, with the wheels being a primary target. A lighter wheel allows finer control by suspension and allows the bike to turn quicker with less input. Note the six, thin, H-section spokes. Take a look at the cut out in the hub. You can see straight through to the wheel spacer and inside dust seal of the wheel bearing. Not much material there. According to Kawasaki, the spoke design allows thinner material for the rim, where weight reduction reveals the highest benefits, yet strength is increased.

Wrapping themselves around those lightweight hoops will be Dunlop’s new D218ZR, which are based on the well-known D208ZR. The new tire benefits from new technology through the use of computers to optimize tread pattern stiffness. This increased stiffness will reduce tread squirm, lowering heat generation and allowing the use of a softer compound while maintaining tire life. The carcass will have a joint-less construction, and the compound itself is made up of smaller-diameter, high-carbon black particles which provide a tighter bond between tread polymers and carbon. The D218ZR is not going to be a D208ZR/GP replacement, but those models will have some of the technology from the D218ZR incorporated into them. I did not sample these during the intro, instead, I rode on a super sticky U.K. made D208GP compound front and a “Not for Highway Use” rear tire, that had the look of a 208GP. Word around the pits was that this rear tire was a cut Japanese Dunlop slick with 208GP pattern tread. Not a bad idea for something on the track with this much power, but it left me with nothing to tell you about the stock rubber these bikes will come with.

Tying all of this together is a chassis born from MotoGP experience, with middleweight dimensions. A short distance between the steering head and swingarm pivot make the chassis very stiff and allow for a long swingarm without extending the wheelbase. Curiously, the swingarm pivot is not adjustable.

Tall frame rails are routed over the engine, rather than bending around the sides as seen in previous sportbike designs. This design allows the midriff of the bike to remain very narrow, allowing the rider to tuck in tightly to the side of the bike. These frame rails also serve as an integral part of the ram air system, channeling high-pressure air collected from the center of the fairing, just above the headlight into the airbox.

The styling of the bike takes many cues from its MotoGP cousin, but its edges are more rounded and give it a more flowing look. Aerodynamics were carefully looked after, with even the ram-air intake area receiving subtle tweaks to reduce aerodynamic drag. The flush fitting LED taillight does its part to that end, as does the factory fitted undertail. Turn signals and license plate holder all unbolt easily for track day duty. The sexy, small and flush turn signals that come on the European models could easily be fitted if the owner has the appropriate connections. The headlight is a multi-reflector type, but only one side lights while on low-beam.

If you haven’t figured it out yet, I’m really impressed with this bike. Still, this is a track only test, and as such, this is not a complete evaluation of the ZX-10R. Considerations for (relatively) long distance comfort, how that track-biased suspension treats the street rider, gas mileage, fit and finish, etc., right down to how well the rear-view mirrors work (you’ll be using those, trust me) were not fully evaluated. And as good as this bike seems to be, keep in mind, as I must, that there are all-new, liter-class offerings from Honda and Yamaha that I have yet to sample. I can say this, however, it will take something special to better this bike. Well done, Kawasaki!

Suspension Notes: 195 lb. Rider w/gear:

Front: Stock Track My Settings
Preload 5.5 lines showing Same Same
Rebound 9 clicks out 6 clicks out 4 clicks out
Compression 7 clicks out Same Same
Ride Height Flush Raised 5mm Raised 5mm
Rear: Stock Track My Settings
Preload 13.5mm Same Same
Rebound 1.75 turns out Same .75 turns out
Compression 3 turns out Same Same
Ride Height 3mm shim 2mm (tire profile
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