’09 KAWASAKI
ZX-6R IS ALL-NEW!
Kawasaki has set out to regain the leadership of the 600 Supersport class, a category it can be credited for instigating way back in 1985 with the release of the first GPz600. Stung by criticism of its 2007-’08 models for being overweight and lacking in mid-range torque, Kawasaki told its engineering team to sort those deficiencies for the 2009 model. Reducing weight from any vehicle that is already pretty well refined is no simple matter. It’s not a case of throwing away some single heavy item, such as a muffler. Each component must be analysed, weighed and redesigned: big total weight reductions are the sum of many tiny weight savings.
Some manufacturers discard an entire model design and start afresh but for the 2009 ZX-6R, Kawasaki preferred to stick with the existing design and develop it further. The result of months of research is a new model that features revised chassis geometry, completely redesigned exhaust and induction systems, new suspension – and a substantial 10kg reduction in overall weight. In many respects, what Kawasaki has done is ‘race tune’ an existing design right from the factory.
 WEIGHT SAVINGS
Kawasaki’s engineering team left no stone unturned in shedding weight from both the engine and chassis. One of the team’s more interesting efforts was to use the centrally located ram-air duct/intake resonator chamber as the mounting point for the instrument panel and rear-vision mirrors, thus getting rid of tubular steel brackets. Other examples of the lengths gone to for weight reduction are a saving of just 70 grams with new, lighter starter and oil pump gears, 170 grams shaved from the transmission itself by drilling the gears and a further 150 grams saved with a new, relocated engine coolant reservoir.
Bigger weight savings came from the use of magnesium alloy for the cam and engine sidecovers (610 grams) and new material and design for the camshafts (400 grams). Like the 2008 ZX-10R, the new for 2009 ZX-6R has a two piece aluminium die cast rear sub-frame, with the rear section able to be removed to go racing. Just as important as total weight savings is where the remaining mass is put. Modern high performance fourstrokes require quite bulky and heavy exhaust silencers to allow the engines to breathe as well as meet noise tests.
To centralise mass, Kawasaki has done away with the once fashionable under-seat muffl er and made an all-new system. This sees the exhaust head pipes exit from the cylinders and curve forward and down to get the required tuned length before joining in a catalyst equipped collector that takes the hot exhaust gases into a ‘pre-chamber’
under the transmission before sending
them out through a large muffler
mounted low on the right-hand side.
MID-RANGE BOOST
At the front of the muffler is a servo motor controlled butterfly valve that increases back pressure at low and medium engine revs to improve midrange torque, then opens to allow the engine to breathe out at high rpm.
Other mid-range enhancing moves are connecting the header pipes from cylinders one and two, and three and four, with short balance pipes. On the intake side, the 38mm Keihin throttle bodies have been lengthened to spread apart the throttle butterfly valves: the main and sub-butterflies are now 10mm further from one another.
There are also new ‘double-bore’ intake funnels (but Kawasaki has yet to explain this mechanism), revised cylinder porting, new camshafts and new ignition stick coils with 12% more secondary coil current. All these changes are aimed at improving the engine’s mid-range rideability. Another change, aimed at improving the engine’s fuelling beyond mid-range rpm, is the adoption of cylindrical guides in the top of the air cleaner box to ensure a more accurate spray of fuel mist from the secondary injectors.
CHASSIS
On the chassis front, Kawasaki started by rotating the engine around the gearbox output shaft so that the cylinders stand more vertically than before. This has raised the engine’s centre of gravity slightly and also meant the repositioning of the steering head 10mm higher than on the 2007-’08 bikes. At the same time, the rake angle of the steering axis has been reduced one degree to 24 degrees with a consequent reduction in trail, from 109 to 103mm.
Those changes aside, the big change is the switch to new Showa big piston forks, as Suzuki has done with its new GSX-R1000. In the case of the ZX-6R, these feature 41mm stanchions with an internal diameter of 37mm.
The main damper piston slides directly on the inner bore of the stanchions, providing a huge increase in the damper’s cross-sectional area.
On the previous ZX-6R with cartridgestyle damper units, the damper pistons measured just 20mm in diameter. That means the new damper pistons provide an almost four-fold increase in surface area to the damping fluid, in turn reducing damping pressure. The idea is to make the suspension action more supple, with a gentler initial movement and greater control as the suspension moves through its stroke towards full compression.
This, Kawasaki says, results in ‘a very calm attitude change as weight shifts forward when reducing speed, and thus greater chassis stability on corner entry.’
Just as on the 2008 ZX-10R, the ZX- 6R gets an adjustable, twin-tube Öhlins steering damper mounted sideways across the frame and connected to the right of the top fork clamp.
BRAKING
Stopping duties for the lighter ZX-6R are handled by the same 300mm x 6mm thick ‘petal’ discs as before, gripped by radial-mount four opposed piston Nissin calipers up front operated by a radial pump master cylinder.
At the rear there’s still a 5mm thick 220mm ‘petal’ disc rotor gripped by a single piston pin-slide (floating) Tokico caliper. The only change is that the rear brake pedal now pivots co-axially
with the footpeg for greater feel.
ERGONOMICS
While many of these changes are aimed at making the ZX-6R a better race track weapon for the 600 Supersport class, Kawasaki has not lost sight of the fact that the majority of these motorcycles are purchased for road use.
Changes to the ergonomics include a narrower front to the seat, which is also 5mm lower, handlebars that are slightly closer to the rider and a slim, waisted fuel tank that makes it easier for the rider to grip between the knees. Fuel capacity is 17 litres.
Initial reports from the bike’s launch to the press at the Autopolis circuit in Japan indicate that a rider of two metres and 105 kg found the new bike very comfortable.
Word is the new ZX-6R will be available in March 2009.
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