During the press introduction of the revised CBR600RR, a Honda spokesman described the middleweight sportbike class as “the core of the industry.” This much is also true for Team Green, which actually jump-started the 600cc sportbike class with the introduction of the ZX600R Ninja way back in 1985.
How critical is this market for Kawasaki? Well, its 636cc ZX-6R was the best selling motorcycle for Kawasaki’s U.S. arm among any of its 2004 products, selling in even greater numbers than its kid’s bikes and dirt machines.
In 2003, the ZX became the first in its class to come equipped with an inverted fork and radial-mount front brakes, not to mention class-leading power from its 37cc-larger four-cylinder engine. It made a strong impression during our 2003 Supersport Shootout, but was held back to third place by unsorted suspension components and an imprecise gearbox.
Just one year later, Kawasaki made some revisions to the ZX’s suspension which helped vault it up to second place in our 2004 Supersport Shootout.
And for 2005-just two years after its ground-up redesign-Kawasaki is bringing us what amounts to an all-new ZX-6R on the 20th anniversary of the Ninja 600R, the first of the super-sporty 600cc machines.
A quick look at the pics reveals the ZX’s most obvious changes: sexier new bodywork and a swoopy undertail exhaust system. But there’re many more unseen modifications that make this new ZX a clear cut above the previous model.
Kawasaki sent us and about 100 other motojournalists from around the world to the south of Spain to sample its new ZX in the twisty mountain roads and on the fun and challenging Almeria circuit. Since I picked last year’s ZX as my favorite in the middleweight class, I was expecting good things from the new package-and I wasn’t disappointed.
Our first day aboard the bikes was supposed to be spent lapping the Almeria circuit, but unwelcome rain blew in to spoil our hot laps. Instead we took the little screamers for a sortie in the nearby hills. Although blessed with a Southern California-like climate, some of Spain’s less-traveled roads aren’t always smooth. This was actually a blessing in disguise, as the pock-marked roads were the perfect test for the ZX’s new Showa suspension. Replacing the previous Kayaba components, the new Showa fork and shock proved to be a huge improvement at keeping the bike composed over bumps. The 41mm fork is much more supple than the old bike, making it not only more comfortable but also better behaved. The fully adjustable rear shock works through a more linear linkage ratio to provide a nice balance that the old bike somewhat lacked.
Good stuff seen here are the new petal-shaped brake discs, Showa inverted fork, larger radiator and daintier turn signals.
Kawasaki altered the ZX’s riding position to make it more like the successful ZX-10R. The steering stem has been pulled back by 13mm and, with less weight on the wrists from closer bars, a rider feeds in less input into the steering, which was ideal in the wet conditions we initially rode in. Also making the ZX more comfy is a seat that no longer slopes toward the fuel tank.
Speaking of fuel tanks, Kawasaki has taken a cue from the CBR600RR. Its new split-seam design houses the airbox in the forward section while the aft portion contains the fuel, contributing greatly to improved mass centralization while also feeling nicely narrow between the knees. A move to oval sub-throttle bodies-a first on any production motorcycle, according to Kawi-helps keep the midsection’s width narrower and are said to offer better high-rpm power. Fine-atomizing injectors in the throttle bodies provide squirt during light-wrist activity, while showerhead-type injectors mounted high in the airbox kick in above at 5500 rpm for a strong top-end rush.
The little Zixxer has enjoyed a power advantage over the puny 600s due to its larger displacement, and that lead stretches further with the 2005 model. Kawasaki has totally redesigned the 636cc mill for more power everywhere. Both the intake and exhaust valves gain one extra millimeter in size for more flow through the new cylinder head, while revised cam profiles aid the lower-end and midrange power.
Sounds like a fatter powerband overall, and that’s the way it feels in practice. It has a very linear powerband for a 600, making it almost seem slower than it actually is. Helping both ends of the rev range is an exhaust valve, the first to be fitted to a middleweight sportbike. Located in the underseat muffler, the valve is shut at lower rpm for some added backpressure that boosts torque, and then opens up at higher rpm, taking its cues from engine speed and throttle position, for a less obstructed flow at high rpm.
The new ZX-6R is said to make 124 horsepower at 12,500 rpm, a gain of about 8 ponies over the ’04 bike’s rating. And by the way my test bike quickly got up to an indicated 168 mph on a deserted Spanish straightaway, I’m a believer. We expect the ZX to be the first 600 (more or less) to top 110 hp at the rear wheel when we finally get a chance to strap it to the dyno.
More power is always better, and for riders with this kind of thinking you might want to shop around for a European-spec ECU for your American or Canadian ZX. Kawi tells us that peak power of its North American versions is down about 5 horsies from the European models due to different ECU programming necessary to meet American noise regulation specifications, which differ (rpm, angle of sound meter, etc.) from Euro standards. The European bike makes its peak power 1500 rpm higher than the U.S, bike (at 14,000 rpm). Peak torque is unaffected. The all-stainless-steel exhaust systems are identical.
There ain’t no replacement for displacement: Corner exits are more dynamic with the king kong motor of its class.
The smooth new curves of the ram-air inlet not only look much prettier, they also contribute to a more proficient system, with a straighter path and more efficient internal shape that is said to bump peak power to 130 hp at high speeds. As a side note, Kawasaki says the 599cc ZX-6RR, also new for ’05, comes up about 7 ponies short of the big-bore version.
For the past several years, steering geometry has gotten more radical, with rake, trail and wheelbase numbers getting ever shorter. Perhaps the tide is beginning to swing the other way. Just as Yamaha has relaxed its twitchy steering YZF-R6 for ’05, so too has Kawasaki with the ZX’s new black frame. Rake goes up a half-degree to 25.0 and 11mm has been added to its trail, up to 106mm. A more upright cylinder angle, from 25 to 20 degrees, makes the engine more compact front to rear, allowing it to be placed further forward in the frame. The result for ’05 is a slightly shorter wheelbase despite a desirably longer swingarm, which now features a braced design for added rigidity. Its engine cases are now beefier, helping make the chassis more rigid and reducing the vibration transferred to its rider.
On the Spanish canyon roads, the ZX proves quick to steer and is especially neutral for such a sharp tool. A new set of lightweight wheels that are similar to the thin-spoked beauties fitted to the ZX-10R aid hurried transitions due to less rotating mass. The gearbox action on the ZX is now better than ever, as the transmission’s shift-drum locator arm receives a new bearing to make it slicker. The ZX retains Kawasaki’s neutral-finder feature that some of us feel have no place on a pure sportbike, as slipping it into neutral from second gear while rolling to a stop is almost impossible. However, this seems to be an easier task than before.
Our forays through the pastoral Spanish countryside included plenty of stops for photography and roadside chats, which gave us ample opportunity to take in the dramatic new styling of the ZX. Its nose is now more graceful, its profile leaner. With the new underseat exhaust, the ZX’s tail gets the most attention. It cleans up the rear end, showing off the delicately shaped new passenger footpeg brackets, the braced aluminum swingarm and the clear-lensed LED taillight. What was once perhaps the ugly duckling of the class has blossomed into a real beauty.
So far so good, although there are two street nits that need to be noted. The narrow-set mirrors can’t see around a rider’s arms, necessitating the most ungraceful of Chicken Dance moves for a rearward view. (Thankfully, we were in Spain, a country that has yet to view speed enforcement as a great revenue generator.) Also, the lightweight aluminum footpegs can be slicker than snot with wet boot soles.
Kudos to Team Green for creating a stylish set of clothes that don’t require flashy decals to make it look exciting.
In the evening prior to our second day, it rained like we were in the Scottish Highlands. Great, I’d travel all the way to Spain and have to write a test based only on about 40 miles of street riding. However, by late morning the next day we had a warming Spanish sun to dry the devilish Circuito de Almeria.
It was almost exactly two years prior that I had my first glimpse of Almeria when I was there to ride the 2003 Ducati 749S. But with several blind rises that lead into tricky corners during the 2.5 miles of undulating blacktop in the middle of rural Spain, the track isn’t easy to master. I needed as much cooperation as I could get from the bike.
In previous years, the ZX-6R might not have been the best mount on which to learn a track, especially in comparison to the rider-friendly CBR and R6. The new ZX changes that, as it offers beautiful steering that is exceedingly neutral, tainted only slightly by a tendency to stand up under braking. The ZX’s extra cubes and new engine tuning results in a much wider powerband than the midrange-flaccid 600s, and its brakes are as good as anything out there.
The engine is not just more powerful, but it’s also more civilized. A new cold-start function makes for easier one-button ignition, and the dual-stage fuel injection performs flawlessly. If you’re a regular MCUSA reader, you’ll know one of our pet peeves is abrupt response from many fuel-injection systems when reapplying throttle from a closed position. The ZX is thankfully devoid of this bugaboo, offering wonderfully smooth throttle response that makes it easy to dial in power from a closed throttle without upsetting the chassis.
Almeria’s increasing-radius turn that leads on to the 900-meter back straight really gave the ZX a chance to stretch its legs. The ZX’s third gear has been made slightly taller to deliver a smooth flow of acceleration during the shift to fourth. The indentation in the top of the fuel tank gives a rider a smidge more room to tuck in “under the paint,” although the more sharply angled windscreen doesn’t offer much protection as previous ZXs.
By the end of the straight, the speedometer regularly indicated 153 mph before I needed to hammer on the brakes. The gauge package is still the same basic unit that has been universally hated for its hard-to-read LCD tach, although the yellow shift light is useful when timing full-throttle shifts. Kawasaki says the ZX-6R is the slipperiest Ninja they’ve yet built, claiming a massive 15% improvement in aero drag that is worth about 10 horsepower at 160 mph! Although much has been made about underseat exhaust systems being more aerodynamic, Kawi engineers say the difference in drag is “not so much.”
When it comes time to bleed off those elevated speeds, the ZX-6R’s new brakes can handle whatever is thrown at them. The rotors are now petal-shaped front and rear, and the front discs increase in diameter from 280mm to 300mm. Just as important for control and feel is the new radial master cylinder for the front brakes; it offers a very firm lever similar to the ’05 Yamaha R6 that impressed us so much, and an integral bleed screw makes getting unwanted air out of the system a whole lot easier. The front brakes are incredibly powerful yet very easy to modulate, and the bike feels less twitchy under braking, perhaps due to the centrally located fuel tank. The twin-piston rear caliper and 230mm rear disc is weak, which I like because it offers a greater range of modulation before locking up in sketchy street conditions.
Corner entries are made easier thanks to Kawasaki fitting the same slipper clutch as equipped on the racer-spec ’04 ZX-6RR. Just hold on the gas as late as you dare down Almeria’s back straight before sending the ZX’s nose diving under the strain from the excellent binders. Then, simply bang down the gears. It matters not how smoothly a rider matches rpm on downshifts because the slipper clutch allows the rear wheel to spin freely without any of the annoying wheel hop that can occur during sloppy downchanges. The ZX’s clutch might be a bit grabby when pulling away from a stop, but the slipper unit itself is awesome-someday every sportbike will have one.
We spent the first half of the day at the track on the stock Bridgestone BT-014s, which proved to have a decent amount of grip for a street tire on a racetrack. A Bridgestone rep in attendance said the Kawi-specific 014 is a half-pound lighter than the normal aftermarket tire. With Yamaha jumping on the 70-series front tire bandwagon, the ZX-6R is the only middleweight with a shorter side profile. Kawi engineers say they chose the 65-series front tire because it is lighter and offers quick handling, yet still remains stable. That said, hanging on to the bars too much under maximum acceleration can induce mild headshake. The solution is to grip harder with your knees.
During our lunchbreak, Bridgestone technicians spooned on sets of their sticky BT-002s. Like most race-compound tires, the 002s are available only in the popular 120/70-17 size. A bit more rear preload was dialed in to somewhat compensate for the taller front tire, yielding similar steering characteristics with the expected increase in grip. Even at the greater angles of dangle made possible by the predictable stick of the soft buns, I never managed to touch down a footpeg.
Note the divot in the top of the fuel tank that allows a rider to tuck in behind the steeply raked windscreen.
Where’s the downside, you might ask? Although Kawasaki didn’t highlight this fact during its Powerpoint presentation, the ZX has picked up a few extra pounds during its transformation, seven to be exact. Kawasaki admits the slipper clutch and undertail exhaust system are heavier than the components they replace, and partial blame must fall on the 40mm taller radiator that offers better cooling. But, since it was the lightest of the bunch last year, its expected tank-empty weight of 392 lbs is still very competitive.
While we’re at it, I’ll point out that the gearbox was occasionally reluctant to make clutchless upshifts at the track. Also, fuel range will be reduced on the ’05 bike since its tank’s capacity has been dropped from 4.8 to 4.5 gallons, matching the Suzuki and Yamaha.
Hmmm, fly a journalist to Spain and get a glowing review of a new bike. Naturally. While we do appreciate the air miles, the truth is the new ZX-6R will finish at or near the top of its class in virtually every category-it’s that good.
Just like in 2003 when the ZX-6R brought radial-mount brakes and an inverted fork to the middleweight class, Kawasaki continues to deliver the trick stuff, becoming the first to offer an exhaust powervalve and a slipper clutch among its peers. Of course, that stuff costs money and the ZX’s higher $8599 MSRP proves it. Now trailing only the $8799 CBR, the Kawi lists for 200 clams more than the R6 and a significant $400 more than the titanium-valved GSX-R600. And coming up from the shadows is the new Triumph Daytona 650, another displacement-bending entry to the class that lists for just $7999. Both Yamaha and Honda have also improved their offerings in this class, so it’s going to be another interesting supersport shootout in ’05 when we bring all the contenders together at once.
But regardless of price, there’s no denying the intrinsic goodness baked into the new ZX-6R. The mission of any sportbike engineer is to make the latest machine faster, better handling and more attractive, and the boys at Kawasaki have delivered, adding the bonuses of improved braking, slicker shifting, a plusher suspension and a wider, more usable powerband.
Hey Kawi brass, they’ll be expecting bonus checks this year.
Talk about the ’05 Kawasaki ZX-6R in the MCUSA Forum