Kawasaki ZXR750

Kawasaki ZXR750 Road Test

Is green good for the environment?

ZXR750The ZXR750, first seen in 1989, is a beautiful machine even by today’s standards. It is sleek and very business like looking. Lavishly finished in a thick coating of paint that is so typical of Kawasaki’s top bikes from the period, the livery mimics the racing styling perfectly. Even at a standstill the ZXR takes on an aggressive stance. It looks every bit a racer on the road with its large section aluminium beam frame and sexy air vents tucked away just below the mirrors, feeding the hungry air box, via a pair of space age vacuum cleaners hoses that disappear into the petrol tank.

In keeping with Kawasaki’s wild and raucous two-stroke machines, the ZXR750 is a thoroughly raw and untamed beast. The engine develops its 100 plus horses in way that never fails to excite while the chassis barely keeps it all in check, adding up to a breath taking journey every inch of the way. It is hard, if not impossible, to ride the ZXR in a manner less than the pure lunatic. The experience is harsh and solid, with few times during the journey upon which to take a breath and catch up with the proceedings. Pulling strongly from as low as 2000 revs, the inline four rises rapidly, up through the rev range, hardening with every increment, ripping your arms out of their sockets by the redline. Despite the tacho dial indicating otherwise, the power does cease to increase at 10,500rpm. However, the engine is willing, and indeed happy, to rev on through this to a searing redline 1500revs further around the dial. This makes for a huge adrenaline rush as the tacho dial speeds clockwise and the air box joins in with tuneful, four-into-one exhaust pipes, chorus.

Kawasaki ZXR750Rider comfort takes a back seat with an intense attack on the senses, bum up and head down all of the way, making every journey a lap of the TT course. The steering is heavy at low speeds while the rear end is under damped and yet over sprung in a way that only late 80’s Japanese machines ever could be. The rear suspension is fatally flawed on the early H models and is a result of a badly designed linkage system, coupled to an inefficient and ridiculously stiff, damper unit.

At its best on smooth surfaces, the inadequate rear suspension and lengthy wheelbase, are easily upset, so choose roads that won’t annoy the ZXR. Having said that the front end is one of the most confident of any bike of the period. Even the benchmark Bimota YB6 from the same year, doesn’t exude the sure-footedness that the ZXR does when on the brakes and tipping into corners. The big and beefy, 43mm forks, are well damped and hold the front wheel rock steady as the engine comes off the throttle and the weight shifts and centres around the small contact patch of the front tyre. This feeling is addictive and when faced with a set of S bends the temptation is to just dive in far too hot and hope for the best. Thankfully the ZXR copes very well and makes the best of a bad, or ham-fisted job, on the way into a tight corner, but falls by the way side a few yards further on when a change of direction is called for.

ZXRKawasaki, mindful of the homologation rules in World Superbike racing, equipped the ZXR750 with as much trick kit as they could get away with for the price. Remote master cylinders and adjustable levers are among the armoury, as is a primitive, yet still effective, reverse torque limiter. This in reality is an early form of slipper clutch and can make the ZXR just as much fun to go down the box, as it is to climb up it in the first place. Great big dollops of down shift soon has the rear end way out of line and performing all manner of tail sliding. Another handy gadget is Kawasaki’s positive neutral finder, a device that prevents the rider from snicking into second gear while at a standstill, hence making neutral a doddle to engage, just drop into first and lift up all the way and there it is, every time.

Looking back, it is clear to see that the original ZXR750 was far from prefect. A heady mix of 80’s thinking, and a desperate desire to create a winning machine on the cheap, is the result of Kawasaki’s labours while others, like Honda, could see a little further into the future. Kawasaki did perfect the beast however, and in a very short space of time but the original H version is there and can’t be erased. It still evokes strong memories among bikes from the period though. During the shoot people were transfixed by the Green Meanie it is difficult to imagine the same effect happening with a red and black version.

ZXR750 Model History

The creation of the World Superbike series in 1988, left Kawasaki seriously lacking when it came to a high performance, road based machine upon which to base a competitive racer. That first year they did compete with a highly developed, but still not quite good enough, version of the dated GPX750. With serious and costly lessons learnt in that first season, a new machine was developed based heavily upon the bikes that had seen much success in the heat of world endurance racing, the ZX7R, and the result was the ZXR750H model. Surprisingly the end result, with its alloy beam frame and race bred construction was heavier than the steel framed GPX by around 5kgs. The factory resisted the temptation to build an exotic, and prohibitively costly, pure bred, race machine as was the case with Honda’s RC30, choosing instead to make a good basis for further modification and create an affordable road machine for the masses. Although the same basic engine layout was retained power was increased by redesigning the head, incorporating huge valves to improve breathing and upping the size of the Keihin carburettors from 34 to 36mm. The use of the old design of engine did save much cost but was the limiting factor in the ZXR’s initial design. It wasn’t until a new power plant was developed and introduced that the bike started to show its true potential.

Kawasaki ZXRThis format remained relatively unchanged for the next two years and, even if the racers weren’t successful, generally customers where happy with the ZXR750. For the H2 model power was upped and weight was shaved ,but with little impact on the scoreboard of the WSB races. In 1991 something had to be done as on the track the Kawasaki was showing lacklustre form. A new, short stroke, 71 x 47.3 mm engine was built, leaving the GPX heritage behind forever, upping power by a good degree while the chassis came in for a good deal of attention too. The wheelbase lost 35mm to aid agility while a diet lost 10kgs from the all up weight. The steering head was steepened, regaining some of the lost agility experienced in the GPX chassis while upside down forks added to the modern feel and looks. For 1991 a pukka race version the ZXR750R was also released, this freed up the designers obligations towards the race homologations requirements and left the standard road going ZXR to meet the customers demands free of the needs of the race track, something the Honda RC30 was incapable of doing.

Kawasaki’s decision to build, and continually develop, the ZXR750 was vindicated completely in 1993 when American Scott Russell clinched the World Superbike title. After a season long battle with Carl Fogarty on his 996cc Ducati the four cylinder 750cc machine emerged as victor. The ZXR continued to be improved throughout the early 90’s eventually becoming a 120bhp plus fire breathing machine. It lost the ZXR moniker during the early part of 1996 becoming equally the popular ZX7R series. The ethos was still the same however, loads of Kawasaki attitude couple with a desire to win races and selling a cart load of roadster machines off the back of this success.

ZXR 750

ZXR750 Timeline

1988 GPX750
Kawasaki struggle to hold their own with the dated, steel frame, GPX machine, both on track and in the world of road going street bikes. Something had to be done and fast if the brand were to maintain their image of total performance motorcycles. A road gong replica of the successful ZX7R endurance racers was planned.

1989 ZXR750H1 chassis number starting ZX750H-000001
A new machine is developed, the ZXR750H. It uses the GPX engine wrapped in an aluminium beam frame. It looked good but was heavy, long, and didn’t go as well as was hoped.

1990 ZXR750H2 chassis number starting ZX750H-015001
The H2 model remained largely unchanged for the following year save for some work inside the engine to get the top end breathing a little stronger.

1991 ZXR750 J1 chassis number starting ZX750J-000001, ZXR750R K1 chassis number starting ZX750K-000001
An all-new machine is announced with a shorter and sharper chassis, upside down forks and a totally redesigned power plant. For the first time, a hotter R version was produced the ZXR750 K1 This proved to be the real McKoy, a real racer on the road.

1992 ZXR750 J2 chassis number starting ZX750J- 013901
Basically the same as the J1, although the rear suspension was sorted out, making for the best ZXR to date.

1993 ZXR750 L1 chassis number starting ZX750L-000001
This was the first ZXR to have Ram-air (one intake on the left hand side of the headlights).
The L is a different beast to the earlier versions and now Kawasaki were “on the money”. A single nose vent fed a pressurised air box and weight was well down. The engine of the previous years Race version (K models) was now fitted to all L models (minus the flatslides and the Close Ratio Gearbox).

1994 ZXR750 L2 chassis number starting ZX750L-020001
Having got the L1 model pretty much spot on little was changed over the next two variants.

1995 ZXR750 L3 chassis number starting ZX750L-030001
this marked the end of the line for the ZXR

1996 ZX7R
The name ZXR was dropped and both in Europe and the US the standard bike was now called ZX7R. The new bike had a shorter stroke/wider bore engine, which gave it much more midrange than previous models, Twin Ram-air intakes, 6 pot Tokiko brakes and suspension was now fully adjustable front and rear.

Kawasaki ZXR750 Specifications

  • Engine – liquid-cooled four-cylinder four-stroke DOHC
  • Capacity – 748cc
  • Bore & stroke – 68 x 51.5 mm
  • Compression Ratio – 11.3:1
  • Carburetion – 4 x 36mm Keihin CVKD
  • Max Power – 105bhp @ 10,500rpm
  • Torque – 56 ft-lb @ 9000 rpm
  • Ignition – transistorised
  • Transmission – 6-speed, wet clutch, chain final drive
  • Frame – extruded aluminium beam frame
  • Suspension – 43 mm telescopic forks unitrack rear
  • Wheels – 120/70 x 17, 170/60 x 17
  • Brakes – 2 x 310mm discs Tokico four piston calipers, 197mm disc Tokico twin piston caliper
  • Wheelbase – 1455mm
  • Weight – 200kgs
  • Fuel capacity – 18ltrs
  • Top speed – 150mph

Kawasaki ZXR750 Gallery

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