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The engine being critical to making the GPz motorcycling's quickest and fastest machine in 1981, Kawasaki's engineers reinforced the cases and went to work filling it with nearly every hot-rodding trick available. Giving a total of 1098cc, the bore was increased to 72.5mm but the KZ1000's 66mm stroke was retained; fit with new pistons and 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 deep combustion chamber were larger intake and exhaust valves, with revised cam timing that featured more lift, but less duration to retain low-speed grunt and flexibility.
Today's vintage super bike enthusiast will find much to like about the GPz1100, but if they haven’t been addressed, the machine does have areas that require attention. The GPzs dated injection is one; but according to Kawasaki guru TJ Jackson the option of grafting standard Kawasaki-spec CV carburetors onto the engine exists. Jackson describes the transformation as straightforward (perhaps to him) 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 more up to date system. Not so easy to solve is the GPz's pressed-up crankshaft. Many, if not most have slipped on the journal next to the primary gear during hard acceleration, meaning they must be removed, realigned and/or straightened then spot welded into place. Not as much a design flaw as a by-product of the engine’s prodigious power and torque. Once these renovations are completed the GPz’s air-cooled, DOHC 8v Kawasaki is substantially more bulletproof than the nails tough Kawasaki four it came from. Cheap now, but for how long? Nolan Woodbury
Now in matt black the engine's newest feature was electronic FI. Made in Japan under license by Bosch the system debuted a year earlier on the KZ1000 Classic. As delivered, the 1981 GPz1100 B1/B2 (1981/2) produced 108-hp @ 8500 rpm, and while it never completely eclipsed the pesky Suzuki for performance bragging rights, the Rebar tough GPz with its beefed frame (larger diameter/thin wall tube steel) and suspensions outperformed the Suzuki were pushed on the track. 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 mile. 1982’s B2 (right) was revised somewhat with black chrome finish, stiffer forks, altered cam timing and a small color matched fairing. Insiders claim Kawasaki drew styling inspiration from Moto Guzzi’s Italian red/flat black Le Mans 850 sports bike
Z1. Nothing other than Vincent’s Black Shadow runs more legend into lore. Recalling all that the Z1 accomplished, succeeding Kawasaki multis had very large shoes to fill. The enlarged line of 1000 fours enjoyed a period of dominance too, but the hunter became the hunted. When the CBX and Yamaha’s XS11 arrived in 1978 the performance gap wasn’t closed, it was smashed into pieces. 1980 saw Suzuki release 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 immediate response was dramatic..
First generation FI muscle