Kawasaki GPz 900R Ninja


Make Model

Kawasaki GPz 900 Ninja / ZX900R Ninja


1991 - 96


Four stroke, transverse four cylinder, DOHC, 4 valves per cylinder.


908 cc / 55.4 cu-in
Bore x Stroke 72.5 x 55 mm
Cooling System Liquid cooled
Compression Ratio 11.0:1


4x 34mm Keihin CVK34 carburettors


Battery ignition, full electronic! 
Starting Electric

Max Power

108 hp / 80.5 kW @ 9500 rpm

Max Torque

8.7 kgf-m / 62.9 lb-ft @  8500 rpm


6 Speed 
Final Drive Chain
Frame Iron, Double cradle frame

Front Suspension

41mm Telescopic forks, air assisted four way anti dive.

Rear Suspension

Uni-Trak air assisted, single shock, 4-way adjustable damping.

Front Brakes

2x 300mm discs 4 piston calipers

Rear Brakes

Single 250mm disc 2 piston caliper

Front Tyre


Rear Tyre

Trail 91 mm / 3.5 in
Wheelbase 1425 mm / 56.1 in
Seat Height 790 mm / 31.1 in

Dry Weight 

228 kg /  502 lbs

Fuel Capacity 

22 Litres / 5.8 US gal

Consumption Average

40.8 mpg

Standing ¼ Mile  

11.3 sec

Top Speed

248.4 km/h / 155 mph

For the GPZ4diameter also rises to 41mm,

EXCITEMENT LEAPS out at you from every phrase of the old road tests. "It was the final fast ride," began BIKE's ex-editor Dave Calderwood in July 1984, as he set out to put 160mph on a speedo for the first time ever. "Swooping south from Huntingdon on a back-road, the GPz900 and I crested a small hill and out front stretched an open clear road, just as I knew it would. No side-turnings for three miles, no reason for the Old Bill to be around... and it was deserted."

He clocked the 160-per a few paragraphs later, of course, and four months after that, in a giant-test on the TT circuit, another tester was just as enthusiastic. "The Ninja came out of the open Waterworks right-hander like a rocker, front end hardly twitching as it recrossed the white line while still cranked over then screamed off up the hill," he salivated before describing the new Kawasaki as undisputed King of the Mountain.

The writer was yours truly and the bike is virtually unchanged, but seven years later the speed-crazed sentences do not trip quite so easily from the keyboard. A brand-spankers GPZ900R - capital Z now, to distinguish it from even-more-ancient air-cooled Kawas — sits in the street outside my window, its H-reg numberplate failing to lift the bike from a humdrum assortment of second-hand cycles.

Seven years ago the brilliant, all-stomping Ninja bloodied the eye with its aggressively-named Firecracker Red paintwork. This bike's alternative colour-scheme, a dull combination of black and John Major grey, seems depressingly appropriate for a drizzly day in 1991. (In fact the brochure refers to Pearl Cosmic Grey, whoever she is.)

Rush out for one thrill-packed last ride? Nah, thanks, I'm staying in to wash my chest wig.

These negative vibes are very unfair, for the GPZ900 is still as good as ever it was. Rather better, as it happens, having been updated in several areas last year. And if it's a slightly old-fashioned motorcycle, at least it also has an old-fashioned price. At £5159 the 900R costs over £1500 less than the ZZ-R1100, almost a grand less than the ZXR750, and exactly the same amount as the ZZ-R600. If that doesn't make you take this bike seriously, nothing will.

Looking back, it's easy to overlook just how significant the 900 was when it was launched at the tail-end of '83. In the preceding decade Kawasaki had built up an unparalleled reputation for big, powerful in-line fours — all of them aircooled with two valves per cylinder. The liquidcooled, 16-valve newcomer represented a radical change of policy, and its success can be judged from the fact that this year's top-of-the-pops 175mph ZZ-R11 uses a modified version of the same unit.

The 1991 GPZ900R, on the other hand, u$es a totally unmodified version: the very same eight-year-old 908cc motor, with its screw-and-locknut tappets, piggyback alternator and cam-drive on the end of the block. Sure, there have been a few minor updates along the way: revised camshaft oil feed, modified camchain tensioner and guide, recalibrated temperature gauge, some fiddling with the airbox and a much-publicised aniti-icing cure for the 34mm Keihin carbs. But the engine essentials, and the claimed output of 113bhp at 9500rpm, are just as they've always been and are still impressive.

Another feature of the engine was the balancer-shaft, novel for a four in '84, that allowed the unusually smooth power unit to be employed as a stressed member of the chassis. The frame combines a steel backbone with an alloy rear subframe. Unlike Triumph's recently-launched backbone frame, the Kawasaki has three narrow top members instead of a single thick one. But you can bet that the Hinckley engineers, whose plans were starting to take shape in '84, we're influenced by the Ninja's design.

The most important changes to the Kawa are elsewhere on its chassis, most notably the front wheel that grew from 16 to 17inches in diameter last year. At the same time both wheels were widened by half-an-inch, allowing a fatter 150-section bias-belted Dunlop to be crowbarred onto the 18inch rear. And the 38mm front forks grew to 41mm in thickness, shedding their hydraulic anti-dive system - like the 16incher, as dated an '80s style statement as red braces and shoulder-pads - along the way.

Brakes were changed, too. The front discs grew to 300mm in diameter, semi-floating rather than solidly fixed (to help pad alignment) and grasped by heftier four-pot Tokico calipers. The rear disc was reduced in diameter to 250mm but received a twin-pot caliper of its own to make amends and keep the pedal in a job.

Brake and clutch levers were binned to make way for four-way adjustable replacements, and a variety of other details were likewise replaced by bits from other models. Clocks come from the ZX-10, handlebar grips from the ZXR750, push-to-cancel switchgear from the ZZ-R600 and mirrors from the 1000RX. This year's only change is a new one-piece handlebar, apparently deemed necessary because the old design occasionally made a worrying (though not dangerous) creaking noise.

It's a wonder the whole bike doesn't creak when you fire it up, for the 900R has been in Kawasaki's range for so long that it has outlasted not only its supposed replacement the 1000RX but also the more recent ZX-10. It sounds the same as ever, of course, whirring and whining and taking a fair time to warm-up. By big-bike standards the Ninja was a very compact machine when it was launched, and it still feels reasonably low and well-balanced now. It's actually slightly longer, heavier (at 5151b dry) and taller than the ZZ-R11, so perhaps it was a relative lack of bulky bodywork that made the lithe-looking 900 seem the smaller bike of the two.

The above list of detail changes is short, so I was surprised to find the mutant Ninja (soon it'll be a teenage mutant Ninja, if not quite a turtle) feeling noticeably different from the old. You'd have to run them back-to-back to be sure, but the new bike's front end felt a little more laid-back and slower-steering than I recall the 16incher. Rake and trail figures of 29 degrees and 118mm are about as close to the sporting norm as Freddie Spencer's collar size, but no complaints there because the Kawa's neutral feel suits its slip into sports-tourer mode just fine. (Perhaps Freddie should try entering the National Rally?)

The anti-diveless forks worked pretty well, too, giving a reasonably firm ride without approaching the taut feel of the big ZZ-R. I was always pretty keen on the way the anti-dive firmed things up when you hit the brakes hard but, in combination with the Ninja's fairly stretched-forward riding position, that set-up was decidedly harsh on the wrists. The newer front end provides greater comfort at the expense of more fork-dive under braking; meanwhile the unchanged, air-assisted rear soaks up the bumps as nonchalantly as ever.

The anchors also proved very adequate, though surprisingly they felt less powerful than the original bike's combination of smaller discs and stone-age single-pot calipers. If anything the old set-up was a bit grabby, and a few riders have gone for a slide up the road after taking too big a handful. The newer set-up is more progressive, but with eight pistons to call on I'd expected a bit more bite from the front stopper. Perhaps it's just a sign of how good the opposition now is.

The engine suffers from such comparisons in the same way. Back in '84, of course, it was the ultimate rip-snorter. In that year my proddy-race GSX1100 was brim-full of illegal Yoshimura gear, yet the bloody bog-stock Ninjas still came steaming past before the end of the Snetterton straight. These days a ZZ-R would leave the 900 for dead and Suzuki's GSX-R1100, 501b lighter as well as 10 horses more powerful, would make it look positively sluggish round Snetterton.

And it's no good kidding yourself that the 900 can hide its age so long as you keep away from a racetrack. The Kawa still storms to warp speed in moments - its rejigged tacho and speedo needles dancing round their dials with as much enthusiasm as their predecessors - when you keep the motor on the boil with the sweet-changing six-speed gearbox. It still tops a genuine 150mph, and it still demolishes the quarter-mile in a shade over 11 seconds.

But the old-style power step at around 7000rpm seems more obvious now that so many big bikes have more beef in the midrange. And the traditional Kawasaki hole below four grand, much improved on the ZZ-R, now intrudes where in the old days you were having too much fun to notice it. There's more vibration than I remember, too. Nothing annoying, but a distinct tingle through seat and pegs above the six-thou mark, corresponding to around lOOmph in top gear.

Even so, on a motorway you could cruise comfortably at that speed until blue lights interrupted your progress. The slightly narrow-looking fairing and seat are impressively efficient, there's plenty of room for both pilot and pillion, and the fuel tank takes a reasonably generous 4.8 gallons. Just load up, point it and go: the Ninja comes with as well-proven a reliability record as any bike and with more performance than all but a few.

It won't turn many heads, it won't make you want to rush out and ogle its engineering, and it might not always inspire you to take it for a thrash just for the hell of it. But the GPZ900R will provide easy speed, vice-free handling and plenty of comfort, plus that all-important bonus of cash in your pocket that you won't get with something equally good and more modern. In impoverished times like these, that combination is enough to make Kawasaki's well-preserved old warrior well worth a serious look

Source Bike Magazine1991