1982 Kawasaki GPz 750

The last - and probably the best - of Kawasaki’s air-cooled 750s
By Margie Siegel
November/December 2010
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The 1982 Kawasaki GPz 750 was the last - and probably best - of Kawasaki's air-cooled 750s.
Photo by Nick Cedar
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1982 Kawasaki GPz 750
Engine: 738cc DOHC air-cooled transverse-mounted inline four
Top speed: 125mph (period test)
Transmission: 5-speed, chain final drive
Weight(wet): 506lb (230kg)
MPG: 40-50mpg
Price then/now: $3,348/$1,500-$3,500

Kawasaki made its reputation in the 1960s with fast 2-strokes and cemented it in the 1970s with the legendary 903cc Z1, a 4-cylinder 4-stroke bolt of lightning. The boys at Kawasaki knew a sporty image sold bikes, and the new for 1982 Kawasaki GPz 750 showed just how sporty a Kawasaki could be. 

The Kawasaki Z1 was critical to Kawasaki’s success. Thanks to the Z’s rock-solid underpinnings, Kawasaki was able to market variants based on it for the rest of the 1970s — and beyond. Its basic architecture supported a new line of sport bikes in the 1980s, the GPz series, introduced for 1981 in 1,100cc and 550cc models. Like all Kawi fours before them, the new GPz sport bikes boasted double overhead cams, plus electronic ignition and triple disc brakes, expected equipment on any bike with sporting pretentions. 

Although the GPz 1100 could claim to be one of the first production motorcycles to sport fuel injection, it wasn’t necessarily the most technologically advanced bike of its day. That issue didn’t bother Kawasaki fans in the slightest, for while GPz’s may have lagged in technical terms behind some bikes, they were undeniably fast and fun. 

The front row of then-popular club races for 550s were heavily populated with Kawasakis, and the bigger GPz 1100 swiftly gained a reputation as an excellent sport tourer.

The 750 arrives
The Kawasaki GPz 750 hit showroom floors in 1982. Styling was directly inspired by its GPz siblings, and its engine, apart from an all-black paint scheme, looked basically identical to earlier Kawasaki 650 and 750 fours. Yet closer examination showed that a fair amount of work had gone into making this 750 special. New bits included a revised cylinder head, ported and polished, and with smaller combustion chambers incorporating specially placed ridges to induce swirl. New pistons with higher domes helped squeeze the incoming fuel/air charge, resulting in a compression ratio of 9.5:1. Revised camshaft profiles and new constant-velocity 34mm Mikunis helped breathing, and an oil cooler kept operating temperatures in check. Exhaust fumes moved out through large-capacity black chrome mufflers that perfectly complemented the all-black engine. 

To help keep things smooth, the engine was cushioned in a double cradle frame with large rubber mounts. A shortish wheelbase of 58 inches (Honda’s CB750F came in at 60.5 inches) encouraged tight turns and easy steering, while air-assisted forks and shocks, adjustable for both preload and rebound damping, took the bumps out of the road. Triple disc brakes with drilled rotors completed the mechanical package, and an arrest-me-red paint scheme accented with loud graphics told the rest of the world this was a bike that meant business. 

Kawasaki marketed the GPz 750 as a light, responsive machine with a high power-to-weight ratio — just the thing for carving canyons or a little friendly competition at the local circuit. True, a curb weight of just more than 500 pounds wasn’t exactly svelte, but with a claimed 80hp the 750 could acquit itself well out on the road and on the track, where Cycle World ran one through the 1/4-mile in under 12 seconds. Compare that to the almost 550 pound, 75hp CB750F and its best 1/4-mile times in the high 12s, and the GPz’s performance appeal comes into perspective.

A successful recipe
The GPz’s combination of go-fast styling and performance evoked massive lust in the sport bike crowd. In 1982, Don Johnson, the owner of our feature bike, was in the military, with little time to spend in extracurricular activities such as lap time improvement. Still, in a show of massive disloyalty to his then-current ride, a 1978 Suzuki, he spent a significant percentage of what free time he had eyeing the wares of the local Kawasaki dealer. “Like a lot of guys, I spent my youth drooling on bikes. They had a 1982 GPz at the local dealer, and I used to go up there and pet it,” says Don. “The dealer thought he had a pervert in his dealership. I wanted to buy it, but I got shipped to Germany before I got the money together. Ever since then, I have had a thing for this motorcycle.” 

Contemporary magazines, equally subject to Kawasaki passion, enthusiastically tested the new 750. Any qualms about the lack of the newest technology (water cooling and 4-valve heads, for example) were put aside to cheer the GPz’s speed, power and handling. 

Even so, testers pointed out a lengthy warm up needed on start, a flat spot in the carburetion, and a slight buzz through the bars. Yet aside from these caveats, the magazines praised the GPz 750 as a versatile, good-handling machine that was comfortable enough to tour on. “The GPz is essentially a stylized, high performance spin-off of Kawasaki’s venerable KZ750E,” said Rider in its October 1982 issue. 

One issue mostly ignored by period testers was the bike’s height: You had to be the size of the average American male to do well on the GPz. In 1983, Rider collected five experienced women riders and sent them out on a tour of California with six bikes, including a Kawasaki GPz 750. Most of the women quickly found that ergonomic problems seriously dampened their enjoyment of the GPz. “It’s big, it’s powerful, and it does not compromise,” stated Ms. Dorde Woodruff, adding, “It proved the most difficult for our group.”

The women found the bike’s forward riding position and 31.5-inch seat height hard to cope with. On tight, twisty roads, Ms. Woodruff preferred the BMW R80ST her group also tested. “The Kawasaki was too much work and a little scary for me there,” she said.

“I must have been the target ergonomic guy when they built the GPz,” Don says, noting his 5-foot 10-inch frame fits the bike perfectly. He takes it on forays into the local hills, and has no problems with the somewhat rearset pegs or the lowered bars. “As a matter of fact, it’s a great bike around town,” he adds.

In 1983, Kawasaki significantly modified the GPz, giving it a new single shock frame, a full front fairing in place of the little bikini fairing on the first bikes, and a more radical engine. Compression increased to 10.5:1 and horsepower to a claimed 85hp, providing more speed at the expense of the 1982 bike’s versatility. While there was muted criticism of Kawasaki’s technology — or perceived lack thereof — in some corners, it was quieted for a time when Wayne Rainey, racing for Muzzy Kawasaki, won the AMA Superbike championship on a race prepped GPz 750 in 1983.

The 1984 version lost the fairing lowers and gained more comfortable bars, while for 1985 the better bars stayed, but the lowers were back. However, 1985 was the last year for the air-cooled GPz. By that time, Kawasaki had its next generation liquid-cooled Ninja sport bikes ready. Yet not everyone was in favor of further progress. As Cycle World said in 1985, “All in all, the GPz is a satisfying motorcycle. But satisfying may not be enough for much longer ... It’s likely to be replaced next year with a 750 Ninja, a motorcycle that will offer not just more performance, but more cost and complexity, as well.”

Don finally gets his GPz
Don Johnson came back from his tour in Germany and resumed his love affair with bikes. He eventually started collecting motorcycles, including the 1970 Triumph currently sitting in his living room. Yet he occasionally found himself thinking about that GPz in the dealer’s showroom way back when, and idly reading the classifieds last winter, he saw an ad for a 1982 Kawasaki GPz 750.

Don immediately got on the horn and requested photos, which showed a mostly stock, nicely kept machine. He was ready to dash out to the seller’s house when reality hit — it was winter, after all, and the trip would have been complicated. So he called his brother, Mike, who lives below the snow line where the bike was located, and Brother Mike agreed to go look at the bike, and buy it if it looked as nice as the machine in the photos.

Seeing the bike, Mike duly called, reporting, “Hey, it looks even better than the photos. Are you sure you want it? If you don’t, I’ll keep it.”

Mike bought the bike and rode it home, and as soon as Don was able to, he showed up with a trailer, ready to settle up with Brother and take the GPz home. It was in comfortable running condition, but had an incorrect seat, lacked the stock grab rail, and had some paint damage caused by a leaky battery.

“I started the search for a correct seat,” Don recalls. “I found one after two hours on a Kawasaki enthusiast website. A friend is really good with upholstery, and the two of us managed to merge the two seats so I had one correct seat. Then I went looking for a grab rail. The guy who had the seat told me, ‘I wish I had known you needed a grab rail. I would have thrown it into the box with the seat.’”

Don repaired it and painted the battery box, baking it in the kitchen oven to give it a hard finish. He replaced hoses, caps and some rounded off bolts, and changed out the fork oil, the air filter, and the oil and oil filter. “Whenever I get a bike home, I change all fluids as a matter of course,” Don says.

The tires were visibly new when he bought the bike, so he left them alone. The bike also had an aftermarket front fork brace, which he’s left in place. Importantly, the mufflers, which are now pretty much unobtanium, were in good shape. “There are tiny gravel dings on the header pipes that you can’t see in the photos, but I know they’re there. I’m looking for a guy who does black chrome,” Don says, explaining that he’d like to renew the pipes’ finish.

Don says that the GPz is at its best on curvy roads in the hills. “It keeps up with traffic, changes lanes smartly, has good brakes and good acceleration. You don’t have to worry about being run over by the car behind you. It isn’t a super handler by today’s standards, but it’s good. I’ve never pushed it very hard, but it won’t embarrass you on a mountain road.”

Don also says the bike performs well on the freeway. “The seat is comfortable. There’s slight vibration in the bars, but not to the point where it’s a bother.” And while he didn’t buy the GPz for economy, he thinks he would notice if the GPz was exceptionally thirsty. “It seems about normal for a bike of this displacement,” he says. Period testers got between 40-50 miles per gallon, depending on how enthusiastically they were pushing the engine.

Summing up his love for his GPz, Don thinks back to the first time he spied a 750. “It’s a chemistry thing,” Don explains. “It’s something that has been with me since 1982. I like classic-y bikes in general and the GPz is classic. I love the way it looks and feels and sounds. It’s a classic with a performance slant.” MC


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