Kawasaki ZXR750
Tht ZXR catching feature were the twin air scoops that curs ed dramatically from fairing to airbox.
Kawasaki 's new race-repUt a h - < d good in rt d. but it was the lime m that resembled ■ factory racer.
Kawasaki’s ZXR750 looked every bit a street-legal raeebike, with its sleek bodywork, race-team inspired paint scheme and a big pair of air duets leading back from its nose towards the uprated four-cylinder engine. The reality was rather more down-to-earth, but an exciting bike for all that. Despite being a much more straightforward machine than purpose-built exotica such as Honda’s RC30. the ZXR matched its good looks with speed, handling and a competitive price that made it an instant hit.
In developing the ZXR. Kawasaki resisted the temptation to produce a high-priced special intended purely as a basis for a World Superbike challenger. Instead, the firm’s engineers combined a reworked engine from the GPX750 roadster with a new chassis based on that of the aluminium-framed ZXR-7 factory racebike. Although the power and weight figures were not spectacular, the result was a rapid and reasonably practical machine.
The 748cc engine was surprisingly unchanged from the GPX unit, considering that it was powering an all-new model with such obvious racing heritage and intent. The GPX format of a liquid-cooled 16-valve four with twin camshafts driven by a central chain remained. Main changes were bigger valves, higher compression ratio and a lightened crankshaft. The peak output of 105bhp at 10,50()rpm was only slightly up on that of the GPX.
Most of Kawasaki’s development effort went into the ZXR’s new chassis, especially the aluminium twin-beam frame that appeared to be stiff enough to justify weighing 81b (3.6kg) more than the GPX’s steel equivalent. Other new features included a bolt-on rear subframe, braced swingarm, multi-adjustable suspension, plus wheels that were wide enough to take racing tyres.
Racy performance
The ZXR’s stretched-out riding position and harsh, solid feel at low speed gave a racy feel, and the Kawasaki had plenty of performance to back it up. Its engine’s response below 2000rpm was poor. But above that figure the Kawasaki carburetted crisply through its bank of 36mm Keihins, storming towards its 12,000rpm redline and its top speed of 150mph (241 km/h).
Handling was solid, stable and confidence- inspiring, without approaching the quick steering of its more exotic race-replica rivals. Although the rear shock was firm, both that and the front forks were well damped, and the big front brake discs gave plenty of bite. Essentially the ZXR was a road bike that worked best on fast, smooth surfaces, rather than a racebike adapted for the street. It was not the most comfortable of bikes but it had character in abundance, and most owners were very content with that.
Kawasal acted quickly to fine-tune the ZXR, adding power and reducing weight slightly just a aunch. For 1991 it was more comprehensively redesigned w ith a shorter-stroke er.grne. lighter frame, steeper steering geometry and upside-down forks. And the same year also saw the release of the limited-edition ZXR750R. with l I8bhp engine, less weight and improved suspension. The R model w as the street-legal racebike that the ZXR750 had always threatened to be.
Russell's World-beating ZXR
Kawasaki's efforts with the ZXR750 in World Superbike racing were rewarded in 1993, when American ace Scott Russell won the championship after a close fight against Ducati's Carl Fogarty. Russell's 750cc bike often lacked speed against the 926cc V-twin, and the Georgian won only five races to Fogarty's 11. But both the green Kawasaki and its rider proved very reliable throughout the season, and Russell held on to take what would prove to be a rare championship win for an in-line four-cylinder machine.
Early ZXRs had firm suspension that worked well on smooth surfaces hut gave a harsh ride on bumpy roads. The twin-spar frame was rigid and the Kawasaki was superbly stable at speed, but lacked the audit of some super-sp Few owners were too worried about that, and the ZXR’s 0iimage made it a big hit.
Specification Kawasaki ZXR750 (1989)
- Engine Liquid-cooled dohc 16-valve four
- Capacity 748cc (68 x 51.5mm)
- Maximum power 105bhp @ 10.500rpm
- Transmission Six-speed, chain final drive
- Frame Aluminium twin beam
- Suspension Telescopic front monoshock rear
- Brakes Twin discs front disc rear
- Weight 452lb (205kg)
- Top speed 150mph (241 km/h)
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