It's no secret that Kawasaki's ZX-6R has been taking a pummeling from the competition for the past couple of years. Although the chassis is one of the better-handling units available, the engine was a little short on steam, a critical deficiency in the ultra-competitive 600 class. And for a manufacturer that prides itself on a reputation for power, it was a situation that bordered on embarrassment.
With the now-standard two-year development window for the ZX-6R approaching in '09, you just knew that Team Green wasn't going to mess around with the next generation 600. And by all appearances, it looks like the boys at Honda and Yamaha better sharpen their swords-the new ZX-6R is heavily redesigned and looking to take names.
A Mini ZX-10R?
Although the physical resemblance to its ZX-10R brother is unmistakable, there's been far more changes than just new bodywork. Both engine and chassis of the new ZX-6R have undergone substantial revamps.
While the 599cc powerplant's bore and stroke dimensions remain unchanged, a plethora of internal improvements have been wrought with the intent of reducing weight and friction while increasing efficiency for more power. For instance, the crankshaft main bearing inserts have been changed to a new material that is claimed to significantly reduce friction by propagating a smoother and stronger oil layer between the journal and bearing surface. The ventilation holes between each cylinder cavity in the crankcase have been revised, and the cam chain guide has been redesigned to a straighter path for less friction. Other changes down below include narrower gears (reducing overall weight by more than 0.5 pounds) with revamped engagement dogs in the cassette transmission, and the oil pump gears are made from a different material to save weight. An additional 610 grams were cut by going to magnesium engine covers.
This shot of the different...
This shot of the different generation ZX-6Rs shows some of the slight construction differences between the new '09 model (foreground) and the old '07-'08 version (background). Note the comparative weld locations and size of the swingarm pivot sections.
The new EFI switches to a...
The new EFI switches to a round main throttle bore (even though the secondary throttle bores remain oval) in order to work with the redesigned intake ports. Even the internal surface finish of the throttle bores was changed in an effort to improve flow.
The cylinder head has undergone major revisions despite retaining the same size valves. The intake and exhaust ports have been reshaped, with a noticeably increased volume near the valve seats contributing to better cylinder filling in conjunction with the ram-air induction. The camshafts have new profiles to enhance low-end and midrange power, while their new chrome-moly steel construction helps drop nearly one pound of weight. New pistons feature different skirt profiles with moly coating (less friction again), with new crown profiles for better combustion efficiency while compression ratio remains the same; even the piston rings have been revamped to provide less tension (for-you guessed it-less friction). The stick coils in the spark plug caps now feature rare-earth magnets that help boost coil output by 12 percent for increased combustion efficiency.
The electronic fuel injection system has also undergone some changes, although it retains the same throttle body size, dual injectors per cylinder and injector angle as before. The previous oval throttle bodies have been swapped for a setup featuring round bores with oval intake trumpets, and the distance between the primary and secondary throttle plates has been increased by 10mm to improve throttle response in conjunction with the redesigned intake ports. Because the airbox lid is slightly shallower to accommodate the reshaped fuel tank, the secondary injectors are now shrouded to protect them from the turbulence that is present in that lower position near the intake funnels.