Kawasaki KZ750: The Understated Big Twin

If ever a machine was worthy of Under the Radar status, it’s the big twin Kawasaki KZ750. Never heard of it? Don’t feel bad, because the truth is, most people haven’t. Introduced in 1976, the KZ750 was the odd-man-out in Kawasaki’s lineup, especially considering the new bikes Kawasaki had planned for 1977, which included the 4-cylinder KZ650 and KZ1000. Matched up against those two machines and the carry-over KZ900 four, the 750 didn’t quite make sense. With its legendary 2-stroke triples a thing of the past, Kawasaki’s performance machines were being defined by four cylinders. So why a big twin?

The Vertical Twin Appeal

Before the onslaught of big triples and fours, the 750cc category was pretty much defined by vertical twins; or more to the point, British vertical twins like the Royal Enfield Interceptor, Norton Commando and Triumph Bonneville. Yamaha made some motion into the category with the Yamaha XS650 vertical twin in 1970, and even more so with the Yamaha TX750 three years later. But compared to its British rivals the XS650 was considered small, while the TX750 was a regrettable failure. By the end of 1975, there were really only two large vertical twins on the market, the 750cc Triumph Bonneville and the 650cc Yamaha XS650.

Looked at from this light, Kawasaki’s move made sense. While the days of Rule Britannia were over, there was still a sizeable community of riders who wanted a big twin. For that group, the new fours were too much. They had two too many cylinders, too many camshafts, too many carburetors and too many spark plugs. For these riders, the best bike wasn’t defined by quarter-mile performance, it was defined by ease of maintenance and dependability. And on that score, the KZ750 delivered.

Engineering and Performance

Unlike Kawasaki’s last big twin, the BSA-clone W650, the KZ750 was thoroughly up-to-date. The 55 horsepower, 745cc twin had double overhead cams, shim and bucket valve adjustment, a Morse Hy-Vo primary drive chain and five forward gears. Vertical twins vibrate, so Kawasaki gave the 750 a pair of chain-driven counter balancers. It worked — mostly. Although smooth at low and moderate rpms, period testers faulted the twin for a distinct buzzing at anything over 4,000rpm, and feared it would shake itself apart at anything approaching its 7,750rpm redline: It wouldn’t, it just felt that way.

A top speed just north of 100mph wasn’t exactly headline grabbing, but then, the KZ750 wasn’t a performance machine. Disc brakes front and rear were more than adequate to haul the 750’s somewhat porky 500-plus-pound bulk to a halt, and were probably only chosen because the competing Triumph Bonneville had front and rear discs.

Styling and Comfort

Styling of the KZ750 was restrained, with a 3.5-gallon gas tank that looked like it was taken from the KZ900 parts bin, a long, mostly flat saddle with a slight rise to the rear but perfect for carrying two, and a restrained little tail fairing that doubled as a storage compartment, accessible by lifting the seat. Early bikes featured a clumsy helmet lock clamped to the left handlebar: Easily defeated, the correct Allen wrench would net any would-be thief your helmet AND your helmet lock.

Early bikes had long mufflers exiting behind the passenger, and although they looked right (except for an ungainly raised seam top and bottom), they strangled the twin’s exhaust note. “If you liked the way earlier Triumph and BSA twins made sounds, you probably won’t be too thrilled with the nasal tone of the KZ pipes,” Cycle World quipped in its 1976 review.

Rider Experience and Reputation

Overall, however, testers gave the big twin good marks. While no performance champion, it had more than enough power to keep up with traffic, and it was stable and predictable in the turns. Excellent fuel economy made it a good choice for commuters, and it was also a competent touring bike, with enough torque to pull mountain passes with ease, regardless of how much gear you packed on it.

The biggest accolades were reserved for its dependability. Thanks to its simple but robust construction, the KZ750 earned a reputation for rock solid dependability, owners piling on the miles with little more than routine maintenance. Kawasaki had gambled that there was a market for a simple, reliable big twin, and they were right. By 1978, the 750 twin was Kawasaki’s fourth biggest seller in the U.S., and it remained so until the end of the decade.

Evolution and Decline

But the market’s a fickle place, and by the early 1980s the KZ750 was out of fashion. Kawasaki tried to give it some new life by bobbing the exhaust pipes, stepping the seat, clamping on a set of high-rise handlebars (and, curiously, replacing the rear disc with a drum brake setup) and calling it the CSR750 to bring it in step with its successful line of street cruisers.

Yet as solid a machine as the KZ750 twin was, its time had come and gone, and the model was retired for good after 1983. Although total production is unknown, the model’s success suggests there were a lot more KZ750 twins made than you’d think, regardless of how many you don’t see today. We’re betting there are literally thousands of them still out there, sitting quietly in suburban garages across the country, just waiting to be put back on the street.

Key Specifications Comparison

Here’s a look at how the KZ750 stacked up against some of its contemporaries:

Frequently Asked Questions

What was the main appeal of the Kawasaki KZ750?

Its primary appeal was its simplicity and dependability. It offered a more traditional big twin experience for riders who found the increasingly complex four-cylinder machines overwhelming, focusing on ease of maintenance and reliable performance.

How did the KZ750's styling differ from other Kawasakis of the era?

The KZ750 featured a more restrained and classic styling compared to the sportier four-cylinder models. It had a familiar tank shape, a comfortable dual seat, and understated tail fairing, aiming for a more utilitarian and less aggressive look.

Was the KZ750 a fast motorcycle?

No, the KZ750 was not considered a performance machine. Its top speed was around 100mph. Its strengths lay in its torque, stable handling, and reliability rather than outright speed.

What were the main criticisms of the KZ750?

Period testers noted a distinct buzzing at higher RPMs and found the original long mufflers somewhat restrictive, impacting the exhaust note. Its weight was also considered a bit on the heavy side for its engine size.

Is the KZ750 a good bike to restore?

Yes, due to its robust construction and reputation for dependability, the KZ750 is a solid candidate for restoration. Parts are generally available, and its mechanical simplicity makes it a manageable project for many enthusiasts.

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