Kawasaki Zx-9

KAWASAKI ZX-9

'94 PREVIEW

CELEBRATING A DECADE WITH NEO-NINJA

WHEN KAWASAKI INTRODUCED THE 900CC NINJA 10 years ago, it released that watershed bike into a class of its own, a class without competitors. By 1992 the Ninja 900 was long gone and the 900cc sportbike class again was devoid of runners. It was, that is, until Honda released its CBR900RR. Now, 10 years after the intro of that first Ninja, there’s a new 900 Ninja. It’s the ZX-9R, shown to the public at the Paris Motor Show in late September. Along with the new Suzuki RF900RR (see Cycle World, November, 1993), this bike is set do battle with the CBR900RR.

Like the Honda, the Kawasaki owes its existence to a smaller machine. But where the 900RR owes its engineering genesis to the CBR600F2, the engineers who designed the ZX-9 used the 1993 ZX-7 as a base model. But this bike is no warmed-over ZX-7. Virtually everything but the swingarm has been redesigned.

The cornerstone of the ZX-9 is an 899cc, dohc, liquidcooled, ram-air-fed Four that is based on the ZX-7’s engine, but with which it shares few parts. Bore and stroke are 73 x 53.7mm and compression ratio is 11.5:1. The crankshaft uses larger crankpins and bearings than the ZX-7, and its longer stroke meant redesigning the crankcase to prevent big-end rod bolts from contacting the case interior. Larger case bolts also are used. Cylinders are composed of wet liners pressed into a cast-aluminum block and radiator size has been boosted by 11.4 percent over that of the ZX-7, while the width of the main oil-pump rotor is decreased by 30 percent to reduce mechanical power loss.

Ignition is handled by a digital system that includes a cutoff at 11,700 rpm, and which fires double-electrode sparkplugs-used, Kawasaki says, to improve low-rpm combustion efficiency. Valves (intakes are 29mm, while exhausts measure 25mm) are set at an included angle of 20 degrees.

Transmission ratios in the ZX-9 remain the same as those in the ZX-7, but the primary reduction ratio is slightly higher. While the ZX-7’s clutch is cork-based, the ZX-9’s is paper-based. Exhaust is 4-into-2-into-l, and uses two rubber-mounting points at the bottom of the engine to help reduce vibration and increase service life.

A twin-spar frame made from welded aluminum sheet carries the engine. The rear subframe is a bolt-on assembly also made from aluminum. The 41mm fork offers three-way adjustability, and uses bushings and pistons that are chamfered to help reduce stiction. The 25mm axle is hollow to reduce unsprung weight. The bike’s shock also is three-way adjustable, and offers a ride-height adjustment via the thread-

ed top shock mount. The same construction technique used on the frame is used to build the swingarm, with aluminum sheet welded to a hollow cast-aluminum piece that forms the swingarm’s pivot area. The swingarm is identical to that of the ZX-7, though its recessed chain adjusters are about a half-inch longer than the 7’s. Pivots run in needle bearings, with an extra caged ball-bearing on the right to prevent deflection. Like the front axle, the swingarm-pivot shaft and rear axle both measure 25mm in diameter and are hollow.

Brakes are 11.6-inch rotors with four-piston calipers up front, and a 9-inch rotor and single-piston caliper at the rear. The front calipers now use differentially sized pistons, as per recent sportbike practice. Wheels are 17-inchers, with 120/70 radial rubber up front, 180/55 at the rear.

What’s missing here are the bike’s main chassis specs-we know the wheelbase is 56.5 inches, the seat-height is 31.5 inches, and the weight, without fuel or lubricants, is 493 pounds, because we weighed and measured our photo bikes. But local Kawasaki reps say the rest of the bike’s numbers haven’t been revealed to them by their Japanese counterparts.

What seemed obvious from the pair of pre-production

prototypes loaned to us by Kawasaki, however, is that the ZX-9R stands a good chance of setting new standards of fit and finish for Kawasaki. Paint is rich and lustrous, plastic parts all fit nicely, and all fasteners look well thought-out.

The bike seems intended for fast sporting use as well, perhaps, as for racing. It has a comfortable dual seat, clip-on bars mounted above the top triple-clamp rather than below, a storage area under the pillion seat, and a windscreen and fairing that look to provide a bit more coverage than might be necessary on a tool of pure competitive intent. All of this should provide rider comfort far beyond that available from the very hard-edged ZX-7.

Though announcement of a complete Kawasaki 1994 model lineup remained several weeks away at presstime, what we do know about the ZX-9R indicates that it will be of particular importance to the company for the coming years. Expect the ZX-9’s price to be competitive. Expect the bike to appear in showrooms no later than early spring. U