Kawasaki ZX-6RR

The NINJA® ZX-6RR sport motorcycle is the racing-homologated sibling of the all-new NINJA ZX-6R. Produced in limited numbers, it is designed for serious on-track performance, strongly reaffirming Kawasaki’s commitment to developing the world’s leading-edge sportbikes.

The NINJA ZX-6RR features all-new, ultra-aerodynamic bodywork with Ram Air, GP-style swingarm, under-seat exhaust system, six-spoke wheels, petal-style disc brakes, inverted forks and a powerful new engine.

Leading-Edge Style

Along with the ZX-6R, the NINJA ZX-6RR is the most aerodynamically efficient sportbike Kawasaki has ever created – even more streamlined than the leading-edge ZX-10R. Specifically, the new fairing helps to divide the air stream farther ahead of the bike; by moving the “bubble” of still air farther forward in the cockpit, the rider experiences less buffeting around the head and shoulders.

The point of convergence – where the divided air streams comes together behind the rider – is critical to aerodynamic efficiency, so Kawasaki engineers designed the tail section to smoothly blend the air together while minimizing turbulence. The result is quicker roll-on acceleration and higher top speeds at the race track, as well as enhanced rider comfort and control.

The new body work also includes a ZX-10R-style central Ram Air duct and a flush-surface LED tail light, as well as an aerodynamic ZX-10R-style front fender for a strong NINJA family resemblance.

From the cockpit, the NINJA ZX-6RR rider will notice several more leading-edge features that put this bike at the forefront of design and performance. Foremost is the new split-seam fuel tank/airbox cover. The rear half is the actual fuel tank, designed to fit neatly between the frame spars and down behind the engine’s fuel injection system, while the front half covers a new, quick-access air box. By centralizing the fuel mass near the center of the bike, chassis responsiveness is enhanced – weight transfers from turn to turn are lighter, and the chassis is exceptionally stable under acceleration and braking.

The advanced split-seam design also enabled engineers to make the airbox larger, thus enhancing engine performance. It also makes filter access quick and easy. Plus, a depression in the top of the fuel tank enables the rider to tuck in for improved aerodynamics.

The final tribute to aerodynamic efficiency is the new under-seat muffler, which gives the NINJA ZX-6RR a slim, racy look.

Exhilarating Power and Performance

No sportbike can garner mass approval on good looks alone, and here again, the NINJA ZX-6RR sets new standards of performance for the middle-weight class. For that, the engine includes a new cylinder, new cylinder head, and 38mm oval-shaped sub-throttle valves fed by twin injectors and redesigned Ram Air.

The NINJA ZX-6RR utilizes oval-shaped sub-throttle technology. Combined with the improved Ram Air design, the oval-shaped throttle bodies increase airflow without making the fuel delivery assembly wider – intake efficiency is improved nearly 20 percent while helping to maintain a slim chassis profile.

The 599cc engine also features revised and polished intake ports, new combustion chambers and larger exhaust valves for improved on-track performance.

Also, the engine control unit has more memory for controlling the exhaust valve and second set of fuel injectors. Plus, the radiator is 40mm taller and features more-tightly packed cores for increased cooling capacity.

The NINJA ZX-6RR features a more durable, smoother-shifting six-speed transmission, and the ratios are similar to those of the 2004 racing kit transmission. It also utilizes a multi-disc wet clutch with a back-torque limiter. Designed to maximize on-track performance, the back-torque limiter helps to reduce rear-wheel hop that may occur when downshifting a high-rpm.

Chassis Features

The matte-black aluminum frame features a shortened the wheelbase and the swingarm pivot point has been moved forward. Combined with a longer, braced aluminum swingarm, the new chassis gives the NINJA ZX-6RR improved cornering performance and high-speed stability. The chassis also includes a steering damper boss on the left frame rail.

The fully adjustable Showa fork delivers outstanding cornering performance and includes TiSiCN coating on the inner tubes to reduce stiction. At the rear, new UNI-TRAK® linkage ratios provide more linear action and the rear shock has a revised damping valve to provide a wider range of racing settings.

Radial-mounted, four-piston front brake calipers deliver exceptional feel and performance; four independent brake pads are used – one for each piston – for more even wear and improved heat resistance. The 300mm petal-style front discs are 5.5mm thick for high heat capacity and the front brake master cylinder uses direct action for better rider feedback. Also, the caliper for the 220mm rear disc brake mounts directly to the swingarm, negating the need for an independent brake tie-rod. The NINJA ZX-6RR has the added benefit of low-expansion brake hoses for improved brake feel.

For exceptional cornering performance, the NINJA ZX-6RR rides on light, six-spoke wheels shod with 120/65ZR17 front and 180/55ZR17 rear tires.

The Cockpit

The riding position is also based on the NINJA ZX-10R. By pulling back the steering head assembly, the distance between the handlebars and footpegs is reduced, which provides the rider with an idealized position for performance riding. Combined with the new frame, seat and fuel tank, the rider sits “in” the bike, rather than “on” it.

The NINJA ZX-6RR’s racing-style instrument panel features a bar-type LCD tachometer, digital LCD speedometer, stopwatch-style lap timer and adjustable shift indicator lamp, which includes Off, Low and Bright settings. A digital temperature gauge, clock and tripmeter are also included.

Features and Benefits

- Designed for #1 performance on the circuit and winding roads
- Polished intake ports, revised porting, new combustion chambers and larger exhaust valves, plus new racing cams, all contribute to increased performance

- Power boosting features includes oval-shaped sub-throttles fed by dual injectors

- Exhaust valve integral with the under-seat muffler improves low- and mid-range engine performance

- Improved aerodynamics give this middle-weight SuperSport the best CdA of any NINJA design to date

- Back torque limiter is standard

- New frame and swingarm with revised chassis dimensions improve cornering performance

- 300mm petal-style front disc brakes with radial-mount calipers and direct-action brake master cylinder provide excellent performance and feel

- Revised riding position based on the ZX-10R lets the rider take advantage of the awesome performance

- To suit non-modified stock racing classes, the six-speed transmission features close ratios similar to those of the 2004 racing kit transmission

- Inner fork tubes feature a TiSiCN coating to reduce stiction and improve suspension action

- Revised damping valve for the rear shock offers a wider range of settings for racing

- Steering damper boss provided on the left frame rail

- Low-expansion front brake hoses improve brake feel

Review

The major technical details of the new ZX-6RR the chassis is identical to the new 6R-save for the adjustable swingarm pivot. The engine, however, is totally different; in order to stay at the 600cc maximum displacement limit for supersport racing worldwide, a highly oversquare bore/stroke configuration (67.0 x 42.5mm, compared to 68.0 x 43.8mm for the ZX-6R, and 66.0 x 43.8mm for the old ZX-6R) is used. Other than the parts associated with that displacement, such as the crankshaft, rods, pistons, cylinders and cams (which feature adjustable cam sprockets on both models), everything else is the same as the new ZX-6R motor, including the cylinder head and fuel injection system which utilizes 38mm throttle bodies (versus the 36mm carbs of the old 6R).
The 6RR's gearbox sports the other big difference between it and its 636cc brother. Although the transmission ratios are identical to the 6R (more closely spaced ratios from third through sixth gear compared to the old 6R), the 6RR has the added benefit of a ramp-type slipper clutch, a first on a production 600. Aimed at eliminating wheel hop on downshifts during the heat of battle, the 6RR's slipper clutch can be adjusted by using optional accessory springs to alter the amount of slip. The shift action itself can also be adjusted via an accessory detent spring.

stiff spring rates (we ended up taking out almost all the preload in the front fork and softening up the rear considerably), ends up feeding a lot of bump energy back into the chassis over rough pavement, and one tester still noted a tendency to tankslap if he wasn't careful powering through transitions. Heavier riders (more than 175 pounds) probably won't notice this as much.

Braking action from the radially mounted four-piston Tokico calipers and 280mm discs is excellent, with stupendous power, progressiveness and feel. We noticed that the 6R and 6RR's brakes on our test units lost a bit of initial bite and progressiveness over time, but their overall power was unaffected; if anything, it helped alleviate some of the oversensitivity that a couple of testers initially complained about (though one felt they were still a little too touchy).

One thing readily apparent when you jump onto the 6RR after riding the 6R or one of the other new middleweights is that the motor is lacking on steam. There just isn't the midrange snap of the 636cc 6R off the corners, and areas where you have to modulate the throttle on the 6R, you can basically hold it wide open on the 6RR. Even compared to the other "real" 600s, the 6RR is down a bit on power, especially in the crucial midrange section of the powerband. Although the power curve is fairly linear and the 6RR revs more quickly than the 6R, real power doesn't begin on the 6RR until 10,000 rpm, requiring you to keep the motor above that point at all times.

Gearing selection is vitally important with this bike; if you enter a corner that has you falling "between gears" (too fast for one gear, too slow for the next), you'll be caught waiting for the motor to catch up to the powerband, resulting in lost time. Granted, this is a racebike, so some tuning with the adjustable cam timing and fuel injection should probably alleviate this problem.

Thankfully, the slipper clutch allows for faster corner entries due to less engine braking, so it's easier to keep momentum up. It is still possible to get the rear wheel moving around a little too much, but this occurs only during extremely hard braking situations where the rear tire is barely in contact with the ground. With MotoGP racebikes employing and perfecting slipper clutch technology, you can bet we'll see more of these units on future sportbikes.

The ZX-6RR uses the 6R's circular LCD bar graph tachometer, and we're growing to hate it. There's not enough contrast to distinguish its reading at a glance, especially in broad daylight. It's a good thing that the shift light is surprisingly bright enough to be visible; the unit has two brightness adjustments (we used the highest one) and can be set in 250 rpm increments up to the 6RR's 15,500 rpm redline.

It's pretty obvious that you'll need to be a serious racer to extract all the potential that the Kawasaki ZX-6RR has to offer. The regular ZX-6R has better power all around, the same suspension and brakes and a $400 cheaper list price. For the average 600 buyer, the 6R is the better purchase, hands down. But racers are not your average buyers, are they?

Source Sports Rider