Dream Machine: 1981-1984 Kawasaki GPz1100

Comparing the Kawasaki GPz1100 with its primary rivals, the Suzuki GS1100E and Honda CB1100F.

| March/April 2018

Kawasaki GPz1100
Years produced: 1981-1984
Power: 104hp @ 8,500rpm (1983-on)
Top speed: 135mph (period test)
Engine: 1,089cc air-cooled DOHC 8-valve inline four
Transmission: 5-speed, chain final drive
Weight/MPG: 551lb (w/half tank fuel)/38-52mpg
Price then/now: $4,399 (1981)/$2,500-$6,000

The early-mid-1980s were a period of unprecedented domination of the U.S. motorcycle market by Japanese makers. Britain's motorcycle industry was dead; in Italy, Laverda was dying and Ducati struggled on, seemingly destined for the same fate until rescued by Cagiva in 1985; and Harley was just emerging from its disastrous AMF tenure. BMW offered a viable alternative — but at a premium price.

This was the era of the "UJM" — the Universal Japanese Motorcycle — a naked bike with an across-the-frame, air-cooled, 4-cylinder, double overhead cam engine of around 1 liter, mounted in a chassis that never quite seemed up to the engine's performance potential. These motorcycles were capable of speeds in excess of 130mph, which, just a decade before, would have been racing territory. And they brought with them reliability, quality finish and durability.

In 1981, and facing serious competition from Suzuki's GS1100E, Kawasaki engineers decided that one more stretch of the Z900-based KZ1000 engine would hold the fort until the all-new liquid-cooled GPZ1000RX replaced it in 1985. To gain the extra capacity, bore was increased by 2.5mm, giving 1,089cc versus the KZ1000's 1,015cc. Bigger valves, revised cam timing, a compression boost to 8.9:1 and Bosch-derived Nissan fuel injection increased power to a claimed 105 horsepower (90 rear-wheel horsepower in Cycle's test). Taller pistons with shorter rods spun a new, lighter crank, and drive to the two overhead camshafts was now by Hy-Vo chain with slipper tensioners. The transmission was the same as the 1000 — straight-cut gears to a 5-speed gearbox — but the kickstarter was eliminated.

The KZ1000-based frame was strengthened and lengthened by around 2 inches, while the rake increased from 28mm to 29mm, giving a long-ish 60.6mm wheelbase. Two rubber engine mountings held the front of the engine, with a single solid mount at the rear. The front fork had factory-preset damping only (although air-adjustable for preload), while the rear shocks had five damping settings. Cast alloy wheels (19-inch front, 18-inch rear) were fitted with 10.2-inch triple-disc brakes. And it was the brakes that caused Cycle World's testers some concern.

"At low speeds (under heavy braking) the front tire would slew from side to side just before breaking loose... At higher speeds the front end of the motorcycle would jackhammer, bouncing the front wheel off the ground, which caused the tire to lock... Stopping distances increased markedly in successive stops as the brakes got hotter, grabbier and harder to control," CW's testers said.

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