2005 Kawasaki Zx-6r
2005 KAWASAKIZX-6R
Middleweight street cheat
DON CANET
THERE’S NO QUESTIONING KAWASAKI’S CONVICtion about taking charge of the middleweight class, both on and off the track. Like its competitors, Team Green offers a multi-bike middleweight sportbike lineup ranging from bargain-biased carryover models to the latest hardware. But what gives Kawi a leg up on the 600class competition is a double-team of ZX-6R and ZX-6RR Ninjas.
CW FIRST RIDE
Offering two bikes so similar in spec might seem crazy to most marketing types but Kawasaki may be on to something.
The 599cc ZX-6RR is a proven winner, earning the 2004 AMA Supersport title (see “Tommy Gun,” page 27). With the limited-production “homologation special” defending corporate honor on the race circuit, Kawasaki is free to work outside the rules of racing with the broader-focused ZX-6R. And what a difference a 37cc dose of cylinder fill can make on public roads! Out in the real world, peak power at high revs simply lacks the practicality brought about by a stout boost in midrange torque. And that is something any rider can appreciate.
While the 636cc ZX-6R gained immediate praise for its engine performance when first introduced two years ago, its ergonomics and suspension calibration mimicked its RR sibling to a fault, thus compromising comfort when used as daily transport. Kawasaki has addressed this with the 2005 ZX-6R, and has done so without losing any of the bike’s exciting circuit-bred character. In fact, it’s said that the powerhouse ZX-10R provided inspiration in shaping the new 6R’s relaxed riding position. A slightly shorter reach to the bars, locating the footpegs a bit farther forward and reducing the saddle’s forward slant has done wonders.
Chassis improvement revolved around shortening the allaluminum perimeter frame, moving the swingarm pivot 13mm closer to the steering stem. This in turn allowed swingarm length to grow 5mm-helping counter the effect drive-chain torque has on rear suspension movement. While the ’05 bike’s 54.2-inch wheelbase is slightly shorter than before, stability has actually been improved by leveling chassis attitude a half-degree, giving the bike a 25-degree rake.
This may not seem like much, but it has resulted in a significant .43-inch increase in trail, now measuring 4.1 inches.
Improved chassis stability is particularly welcome as Kawasaki’s engine department has been equally hard at work extracting performance gains from the liquidcooled inline-Four. Because the engine already enjoys a low-to-midrange power advantage in the class, efforts focused on improving top-end output. A new cylinder head featuring larger-diameter intake and exhaust valves actuated by ’03 race-kit
cams has improved breathing. The surface of the intake ports appears smooth and polished
thanks to a new postcasting process. Another point of interest is a
fuel-injection system that now employs showerhead secondary injectors placed above the velocity
stacks, yet one more example of race technology finding its way to the street. While the 38mm throttle bodies feature primary and secondary throttle valves-not unusual among today’s performance bikes-the use of oval-shaped secondary throttle butterfly valves is an industry first. The elongated venturi design has allowed better airflow without the need to increase throttle-body spacing, which would have spread the frame spars and thus splayed the rider’s knees farther apart. Kawasaki claims the additional intake area has improved induction efficiency by 20 percent! Who says you can’t have it both ways?
Spent gasses now exit through a stainless-steel 4-into-l exhaust featuring an underseat muffler. Balance tubes pairing the head pipes and a servo-controlled exhaust valve located high up where the tailpipe meets the muffler do a very good job of smoothing power delivery. The tailpipe routes up through the right side of the nicely sculpted swingarm, a cool detail that maintains the bike’s clean looks.
Current styling trends aside, the change to the underseat muffler is said to have played a key role in improving the bike’s aerodynamics. The all-new bodywork was designed to reduce air turbulence around the rider and shorten the point of airflow convergence behind the machine. Kawasaki says the ZX-6R has the lowest drag coefficient of any Ninja to date-said to be worth about 10 horsepower at 155 mph. That is, less power is required to overcome drag, which should increase top speed.
Speaking of slick, Showa suspension was chosen for the new bike after testing revealed it had less friction and improved suppleness in initial travel compared with the Kayaba units used in the past. That’s a good thing, because ride quality and comfort were the missing elements that kept the first-generation 636 from becoming the undisputed middleweight champion of the world.
Attending the new bike’s world press launch held last December in Almería, Spain, gave a taste of the machine on the track and surrounding mountain roads. We were greeted with wet roads, which if nothing else tend to expose any deficiencies in the smoothness of power delivery. Throttle control proved excellent, and there were no discernable steps in the powerband. I also noticed right away how slickly the bike changed gears. Later, a Kawasaki engineer pointed out a roller bearing added to the shift mechanism that rides alongside the shift drum index star.
Further refinement is also evident in reduced engine vibration, credited to a rebalanced crankshaft and strengthened crankcase. There’s still a bit of high-frequency buzz felt through the grips, and vibes trickle through the footpegs when revving the engine past 6000 rpm.
The saddle is well-padded and has nicely contoured edges. The seat skin has a faux carbon weave that offered my leathered tush the right amount of grip to feel secure under hard acceleration, yet I was able to slide freely sideto-side when adjusting body position.
A spacious dished pocket at the rear seat step along with a new recess in the fuel tank top makes slipping under the paint into a full tuck a natural fit. One downside for me was that when sitting upright the top edge of the windscreen was smack in my view of the tachometer. Not that it really mattered, as I’m no great fan of the Kawasaki’s LCD rev-counter, which I find difficult to read at a glance. The saving grace is a programmable shift light. I’d suggest setting it for a 14,000-rpm short shift—if you can really call it that-because running up to the 15,500-rpm rev ceiling doesn’t seem to offer any gains.
Because my 6R’s front brake lever was positioned too high, I removed the toolkit from under the passenger seat-due to the muffler placement, there’s no storage space for anything else-and discovered the reason for the odd lever position.
One of the ’05 updates is a Nissin radial-style master cylinder-nice feel, but unfortunately its brake line attachment point contacts the fork leg. Sliding the assembly away from the fork is limited by contact with the switch housing, but did allow just enough lever rotation to suffice—just!
While the tools were out, I explored the Showa suspenders’ range of damping adjustment. I found notable improvement here over last year’s bike, particularly with the rebound damping. You can now quicken movement of the return stroke to suit general everyday riding, where comfort often takes priority over a need for ultimate chassis control. I was bummed to see that the rear shock retains the “dreaded” threaded collar-style preload adjustment. While it’s true that this allows finer tuning ability, it doesn’t allow quick ’n’ easy roadside service, as does a stepped collar.
But hey, when you’re a pampered journalist, you have Kawasaki techs to get chassis settings dialed-in for you. Back at the Almería circuit, I spent a halfday riding the bike with its standard-fitment Bridgestone BT-014 Battlax radiais and the afternoon riding on Bridgestone BT-002 Racing Type 3 tires.
The bike’s handling proved exceptionally sweet with the street tires. Steering felt precise, light and neutral, stability rock-solid and the level of grip in the cool conditions downright impressive. The change to race rubber brought a hint of headshake when cresting a couple of rises around the circuit. The standard front tire is a 120/65-17 while the race tire was a taller 70 series. Reducing rebound at the rear and spring preload up front helped settle the bike. Steering effort also increased slightly with the tire change, but even so, working side-to-side though the track’s secondgear chicane and other pair of thirdgear transitions took little effort. While claimed dry weight is up a couple of pounds, the bike has lost weight in a most critical area, that of unsprung mass, and now sports feathery ZX-1 OR-type wheels. Front brake rotor diameter has increased from 280mm to 300mm, but the discs feature the lOR’s petal design to offset any increase in weight and inertial effect. The system certainly shows no lack of stopping power. The four-pad Tokico radial-mount calipers and new master cylinder proved very effective at converting speed into heat with a moderate two-fingered squeeze.
And now for the best late “braking” news to hit the street this year: The ZX-6R now comes equipped with a slipper clutch that eliminates rear-wheel hop, even when banging multiple downshifts. This is the same clutch previously exclusive to the RR model.
Yep, I told you Kawasaki is committed. . .or perhaps should be! Then again, lunacy often rides the same line as sheer brilliance. Count the 2005 ZX-6R in the latter category.
