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Monday, 08 September 1997 |
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Page 1 of 3
| Kawasaki ZX-6R, First Ride |
By Tom Montano |
| Mr. Takashi Hiraga is the man behind the engine design of the new Kawasaki Ninja ZX-6R. His goal was to produce a lighter, more powerful engine and, as always, an environmentally friendly one for the concerned Californians. What he came up with is the typical haul-ass Kawi motor with three more horsepower at the top and no loss in the low or mid-range. This has been achieved by cutting the intake length down 7 mm and redesigning the combustion chamber. |  |
| Of course, other refinements had to be made to complement these modifications. The redline is now up to 14,500 from 14,000, and the new combustion chamber was developed directly from the '96 ZX-7R Superbike. This gives the little Ninja a higher 12.8:1 compression ratio, and it even burns cleaner. Kawasaki was able shave 3.5 kg of weight off of the engine. Magnesium valve and clutch covers are 33% lighter and a reshaped oil pump cover cuts 103 grams off the old style, which in total is a weight savings of 77%. |
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The head on the ZX-6R (J1) has a new intake valve assembly as well. The tappet surface where it contacts the cam lobe is changed from flat to slightly crowned to improved durability. The retainer's collar diameter has also been changed for a more uniform spring pressure on the retainer. Finally, the valve collet's groove diameter has been slightly reduced for more accurate mating between the collet and valve. Intake and exhaust cams lost 110 grams and gained new, smaller, lighter cam sprockets. |
| The cylinder, which is obviously lighter by feel, is made out of a composite-plated all aluminum material and is now linerless. This design cuts 930 grams off the old cylinder even with the additional 5 mm added to the bottom of the skirt to reduce piston slap.
The piston crown is reshaped in order to match the new combustion chamber and to bump up the compression. Crankshaft weight is always important and the new unit is reduced by 890 grams (12.3%). This really makes a difference in spinning up the motor. A smaller flywheel and rotor don't hurt either. Now that the motor can spin higher revs, the connecting rods needed to be beefed up to deal with the increased power output. You wouldn't want to throw a rod on the bank at Daytona or, as in my case, on the Sulby straight at the Isle of Man.
The housing width of the clutch assembly has been shortened by 5.6 mm, and the pull rod is drilled out for weight reduction. The steel clutch plates are reduced in thickness from 2.3 mm to 1.6 mm, which saves 260 grams, but the surface area is the same. The release shaft has also been turned down for lightness as has been the oil pump drive shaft, saving 86 grams. The oil pump cover is smaller, and fifth gear has been replaced.
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