Kawasaki’s all-new ZX-6R is just that — all new. The factory has developed a brand-new engine in a spanking new, twin-spar aluminium perimeter frame, blending the best features of the outgoing 636cc ZX-6R and the limited-edition 599cc ZX-6RR track bike into a single package.
The new Kawasaki engine was completely redesigned from the cases up — the first in the ZX-6 range in 10 years. With a meaty mile-wide power band and the ability to rev to ultra-high limits when it needs to, the liquid-cooled inline four engine produces loads more mid-range grunt than either of the units it replaces.
The factory is quite unambiguous about the focus of the design team. “Let other models talk about user friendliness,” they say. “This bike was designed to take home the trophies, set the quickest lap times and be more exciting to ride than anything else in its category.”
Kawasaki designed the new engine around low-friction components that are smaller, lighter and stiffer than those previously used. This makes for extremely rapid responses to throttle input, and allows the engine to be about 40mm shorter and narrower than the unit it replaces. Bore and stroke, at 67mm by 42,5mm, remain unaltered from those of the ZX-6RR track tool, and the compression ratio is the same, at a heady 13.9:1.
Aluminium valve spring retainers and lightweight forged pistons were used to contribute to the engine’s high-revving capability, and the compact new valve train helped reduce the engine’s overall height.
Shorter throttle bodies provide improved over-rev characteristics, allowing riders to run the motor harder into corners rather than waste precious milliseconds changing up a gear just before needing to brake again.
The throttle bodies also now feature smaller diameter bores to improve mid-range torque. Computerised flow analysis led to the evolution of extremely sophisticated intake ports, and this technique was also applied to the engine’s internal coolant passages to help take the heat off the highly stressed moving parts.
The 2007 ZX-6R is loaded to the gunwales with track-bred technology.
There’s now a close-ratio cassette transmission that enables track specialists to change easily internal ratios in the pits, and a superb slipper clutch to prevent wheel patter under deceleration. A gear indicator now leaves the rider in no doubt over what cog was selected in the heat of battle.
A pre-chamber located beneath the engine feeds a lightweight under-seat silencer, improving mass centralisation, and redesigned header pipes enable the engine to clear its throat more effectively at high revolutions.
The compact design of the new engine allowed the design team to reduce the frame dimensions accordingly, and the factory tasked a former 125cc Grand Prix rider, as chief test rider, to develop the machine along the lines of a lightweight racer in terms of handling, with the focus on high entry and mid-corner speed.
The result is astonishing — a powerful middleweight performance motorcycle with the handling attributes of a lightweight Grand Prix racer. The tri-axis crankshaft and transmission layout idealises the machine’s centre of gravity and reduces the amount of weight transfer between the front and the rear. This makes life much easier for the suspension and tyres, and allows the professional or amateur tuner more freedom when adjusting suspension settings. The Ninja ZX-6R holds a tight line on the racetrack, and responds instantly and precisely to the rider’s every command.
The suspension of the new Kawasaki is class leading. New 41mm inverted-cartridge front forks position their main springs at the bottom, completely immersed in oil, to minimise cavitation and maintain stable performance under track conditions.
The rear suspension now utilises a pillow-ball spherical bearing upper mount in place of the earlier bushings, to generate a more direct feel and improved feedback. The machine also comes with a set of 1mm shims that can be inserted at the upper shock mount to adjust rear ride height. Both front and rear suspension components are fully adjustable for preload, compression and rebound damping.
Kawasaki, with decades of experience in aviation technology, has always led the field in terms of aerodynamics, and the factory claims that the new ZX-6R is the most aerodynamically efficient Ninja yet, thanks to slick new bodywork, compact projector-beam headlights and the small under-seat silencer that allows the tail section to be much narrower than on the old machine.
Kawasaki has, with the new ZX-6R, developed a new sporting motorcycle that replaces two excellent models and surpasses them both by a significant degree. This uncompromising track tool will arrive in South Africa towards the end of November, at a price yet to be determined.
On the net
Kawasaki SA