1987 Kawasaki 750 Ninja

1987 KAWASAKI 750 NINJA

RIDING IMPRESSION

Returning to the 750 Sportbike Wars

AT A TIME WHEN MONSTER MAchines of 1000cc or more were most influential overseas, the Japanese domestic market was (and still is) legally restricted to a 750cc displacement limit. Usually, 750cc models have been based closely on 900cc to 1000cc monstercycles: The 750s were simply smaller-displacement versions. Consequently. these 750s were truly oversize, penalizing total performance.

That changed when racing rules changed. Formula TT, Fl and Amer ican Superbike racing rules restricted four-strokes to 750cc displacement. Soon. Yamaha, Suzuki and Honda each presented 750cc models made by dedicated design, lightweight ma chines with high total performance. And although Kawasaki'sGPz75OR, based on the 900 Ninja. was a good machine, it was at a sizable disad vantage compared to the dedicated design 750s made by the other com panies. Now the GPX75O has been introduced to blov~ out these disadvantages.

In styling, the GPX is similar to the 1000 Ninja introduced earlier for ex port markets (no surprise there; the same designer styled both machines). Its lines are smooth if a little fat, and definitely macho. But inside the body. all the details are new and of a different design. Especially the en gine. Gone is the unique layout of the big Ninja engine with the cam chain placed at the right end of the crank. Now the chain is centrally located, between the No.2 and No.3 cylin ders. The alternator is still placed be hind the cylinders, but now is driven by a multi-rib V-belt. This makes al ternator removal for racing a trivial matter. The overall result is a light and compact power unit.

This new engine also uses a revi sion of traditional Kawasaki cylin der-head design. Rather than looking like a 900 or 600 Ninja valve train, the valve gear of the GPX more closely resembles that of a Ninja 250. Individual rocker arms open each valve, with a threaded adjuster at the pivot end of each arm. Overall, this system reduces moving valve-system weight by 30 percent, and mechani cally, the engine is safe up to 14,500 rpm (though the redline is set at 11,000 rpm).

Kawasaki has a new 750 Ninja, and it `s alreadi' on sale. But not here. Not vet. In June, Kawasaki announced its new GPX75OR to the Japanese motor ci'cling press: shortly thereaftei~ the bike appeared in Japanese showrooms. The GPX is a replacement for tile GPz75OR, a modelprei'iousli' available in Japan tiwt was simph a 900 Ninja wit/I a smaller bore and stroke. And af ter a revision of its name, along wit/i sonic detail changes for the U.S. mar ket, tile new GPX75OR will become the first 750 Ninja ever sold in this country In Japan. 750s are legal/i' liniited to 77 horsepowei; but the export version of the 750 Ninja will make close to 108 horsepower. In addition, tile turn sig izals will have wider spacing. and the paint and trilil will be different. But other than that, the Japanese and US. versions of the new 750 will be identical. Because the GPX75O was released in Japan so niuch earlier han in the U.S. (750 Ninjas will be in dealerships this fall), we offer this riding impression from our sister magazine. Cycle World Japan.

Further performance improve ment comes from weight reduction. Despite the current popularity of alu minum frames, the GPX75O frame uses high-strength steel tubing in an orthodox double-cradle layout. But compared to Kawasaki's previous 750-class performance model, the GPz7SOR, the GPX has had its over all weight reduced by 29 pounds through careful detail design and by using rectangular aluminum tubing for the bolt-on seat sub-frame.

In the metal, the first impression of this GPX75OR is of the quality of its finish: the paint is excellent, and small items such as brackets and fit tings are carefully finished. The gen

eral design is plump and sensual; but the total dry weight is claimed to be 430 pounds, so the GPX feels lighter than it appears.

Although fitted with clip-on-style, separate handlebars, the GPX has a riding position that is not too low, and a 5’ 9" rider can easily sit in a relaxed posture. Thanks to this room, long rides should be comfortable, and°even a passenger won’t suffer.

As a matter of course, the engine has enough torque, even from low engine speed, and so city riding is no trouble. This applies to the Japanese model, however; export models are scheduled to have more than 100 horsepower and be capable of maximum speeds exceeding 150 mph. As a result of the high outputs, there is a possiblity that, even for a 750cc machine. torque will be reduced at low and medium speeds, and that unique capability of a large-displacement machine to accelerate briskly without shifting gears will be damaged. Nevertheless, on the road, the Japanese GPX750R gives hardly any feelingof the slight dip in torque that Kawasaki’s own dyno chart shows at around 5000 rpm. And despite its good low-speed torque, the GPX accelerates through the lower gears in a big hurry while squealing its wide, 140/70 rear tire.

Although the GPX is lighter in weight than the 900 Ninja. its han dling is rather stable, similar to that of the 1000 Ninja. Steering isn't quick, but rather there is a neutral feel, with no imbalance between front and rear tire traction, and no uncontrollable feeling while lean ing-and the GPX can be pitched to a deep cornering angle with confi dence. When pushing hard, care must be taken with the engine; it revs so freely that it doesn't hesitate to run high into its red zone. No such con cern is required with the brakes; they are very reliable and trustworthy (with a new dual-piston caliper de sign that utilizes a larger-size leadin~g piston to equalize brake-pad wear). so it's possible to dash deeply into corners at high speed.

Being a d~di~ated 750cc design. the GPX-R is better equipped to compete with the likes of 750 GSX Rs, VFRs and FZs. With the intro duction of this machine, Japanese us ers who preferred to pay a premium to buy re-imported 900cc or 1000cc machines may change their notions. And perhaps in America, 900 Ninja fans may find new life in the 750 class. -Koichi Hirose

KAWASAKI

NINJA 750