Kawasaki GPz 1100 – Vintage Motorcycles Online

6 Jan 2015 | Author: | Comments Off on Kawasaki GPz 1100 – Vintage Motorcycles Online
Kawasaki GPZ 1100

Kawasaki GPz 1100

Kawasaki GPz 1100 ( cont )

No other bike besides the Vincent Black Shadow has caused legend to grow into lore. Taking into account all that the Z1 accomplished, succeeding Kawasaki multis had very large shoes to fill. Even so, Kawasaki’s line of KZ900/1000 fours enjoyed a period of dominance during the mid-1970s, but the hunter became the hunted and by 1978, Suzuki’s GS1000, Honda’s CBX six and the Yamaha XS11 had closed the gap.

In 1980 Suzuki released the brilliant 16v GS1100 and the KZ found itself in the ring with not only a stronger puncher, but one with better footwork. The gauntlet thrown, Kawasaki’s response is pictured here.

The engine being critical to making the GPz motorcycling’s quickest and fastest machine, Kawasaki’s engineers opened the cases and went to work. Using nearly every hot-rodding trick available, the bore was increased to 72.5mm while the KZ1000’s 66mm stroke was retained, fitted with reshaped pistons and modified connecting rods. The roller-bearing crankshaft was lightened by using pork chop-shaped flywheels, and both the clutch and five-speed transmission were strengthened.

It’s interesting to note that Kawasaki stayed with the 2v per cylinder arrangement, but inside the GPz’s deeper combustion chamber were larger intake and exhaust valves with revised cam timing that featured more lift, but less duration to retain some low-speed grunt and flexibility. Very much a reworked 903, many owners take great pride in the fact that under the GPz’s angular bodywork lies the soul of the original Z.

Painted all black, the engine’s biggest feature was electronic fuel injection. Made in Japan under license by Bosch, it debuted a year earlier on the KZ1000 Classic. As delivered, the 1981 GPz1100 B1/B2 (1981/2) produced 108-hp @ 8500 rpm.

Kawasaki GPZ 1100

And while it never completely eclipsed the pesky Suzuki for performance bragging rights, the raw boned GPz with its revised frame (larger diameter/thin wall tube steel) and suspensions actually outperformed the big GS when both bikes were pushed in track tests. While on the subject, the GPz drew enthusiastic reviews; Cycle Guide ran a best time of 11.18 in the quarter mile and recorded that the hard charging Kawasaki reached its top speed of 135 mph in less than half a mile.

Today’s vintage super bike enthusiast will find much to like about the GPz1100, but if they have not already been addressed, the machine does have a couple of warts that require attention. The first is the bike’s fuel injection. According TJ Jackson . our local Kawasaki guru at Eastside Performance in Mesa, AZ . the system is hopelessly out of date and not supported.

He has successfully replaced it with standard Kawasaki-spec CV carburetors and describes the transformation as straightforward, with improved reliability. The machine’s digital ignition (which runs on a separate circuit) can be left in place, but many owners choose to fit a modern Dyna. Not so easy is the GPz’s Achilles heel; its pressed together crankshaft.

Most, if not all have slipped on the journal next to the primary gear, meaning they must be removed, straightened then welded to prevent future failure. Not as much a design flaw as an oversight by Kawasaki when the bike was produced, once this repair/modification is performed the air-cooled, 8v Kawasaki is as bulletproof as any. Aftermarket support is rated as outstanding.  Nolan Woodbury

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