Kawasaki KZ750

Under the radar
By Richard Backus
March/April 2009
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Kawasaki KZ750
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Kawasaki KZ750
Years produced:
 1976-1983
Total production: N/A
Claimed power: 55hp @ 7000rpm (1976)
Top speed: 103mph (period test)
Engine type: 745cc OHC, air-cooled parallel twin
Transmission: 5-speed
Weight: 504lbs (w/half-tank fuel)
Price then: $1,975 (1976)
Price now: $500-$1,750
MPG: 45-55

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
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.

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 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.

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.

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.

Two-cylinder alternatives to the KZ750
1977 Yamaha XS650

- 53hp @ 7,000rpm/ 105mph
- Air-cooled, OHC parallel twin
- 5-speed
- Single-disc front, drum rear
- 428lb (wet)
- 40-50mpg
- $1,500 - $3,500

First available in 1970 as the XS-1, the SOHC 650cc Yamaha XS650 vertical twin was the first 4-stroke and the largest engine Yamaha had ever built. Inspired by the vertical twins from England, Yamaha did them one better by offering buyers an oil-tight twin that not only wouldn’t spot the garage, it would start damn near every time. Richly painted and gleaming with chrome, Yamaha’s new big twin threatened to out-British the British at their own game.

Until you rode one, that is. Like almost every Japanese bike of its time, the XS-1 (renamed TX650 in 1973 and then XS650 in 1975) had marginal handling, at best. Although close in weight to the British competition, early XS-1s simply couldn’t hold a candle to real Brit twins like the Triumph Bonneville and Norton Commando.

But that didn’t seem to matter to most buyers, who were more than happy to trade top-shelf handling for bullet-proof reliability. Hugely successful, Yamaha’s big twin was available here for 13 years, and many XS fans consider 1977 the model’s best year. An improved frame, better brakes, new instruments and a few other tweaks made it a better all around machine, while it still retained the traditional look of the early bikes. Cheap and reliable, the XS is possibly the perfect classic rider.

1977 BMW R80/7
- 55hp @ 7,000rpm/ 110mph
- Air-cooled, OHV opposed twin
- 5-speed
- Dual disc front,  drum rear
- 473lb (wet)
- 45-55mpg
- $2,500 - $4,500

Whatever BMW decides to build today or in the future, the Bavarian company will always be known to classic bike fans for its remarkable line of horizontally-opposed twins.

Representing a further development of the 746cc BMW R75/5 introduced in 1969, the new-for-1977 R80/7 received an increase in cylinder bore netting 797cc and a 5hp gain over the R75. Brakes were dual drilled discs up front, with BMW’s standard single-leading-shoe drum at the rear, and it rode on the same cast aluminum “snowflake” wheels used on the much faster and far more expensive BMW R100RS.

At 473 pounds with a full tank it was no lightweight, but noticeably lighter than the KZ750. Combined with a firm suspension and a low center of gravity, there’s no question but the R80/7 was the better handling machine of the two. Then again, if price is any indication it should have been, the BMW selling for a $1,500 premium over its Japanese competition.

Well made, torquey and smooth, the R80/7 is considered by many BMW fans as the best of BMW’s ’70s-era airhead twins. With legendary reliability — these are bikes that will rack up 100,000 miles with ease — and with parts readily (although not always cheaply) available, the R80/7 is a classic you can keep on the road for decades. MC 

Read more about the other motorcycles mentioned in this article: 
• 1968 Royal Enfield Interceptor: England's Forgotten Twin 
• 1976-1980 Triumph Bonneville T140V  
Yamaha XS650
Yamaha TX500 
Ten Days with a 1973 BMW R75/5 
1977 BMW R100RS 


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Post a comment below.

 

TimKern
5/8/2014 9:24:09 AM
Here's my two cents' worth: Love my KZ750B. With new tires and a Corbin seat and the previous owner's orange/flame paint job, this big ol' bike gets old-school riders pumping. Starts on one or two kicks, which is good, since the starter clutch (same part as in the tiny KZ400) is weak. Had several Yamaha 650s, and like the looks, but not much else. Easy starting, but their bad handling is made worse by modern tires, which afford too much grip and torque the chassis even worse. Uncomfortable to ride in any mode, they're best parked outside the cafe. Didn't have an R80, but the R75/5 I bought for my Dad was fast enough and comfortable enough and totally reliable. It was just so tall that neither he nor I ever liked it too much. He preferred his 305 Dream, and I much preferred my R69US.

Nick Howell-Ives
1/7/2011 11:12:04 AM
You were correct in every respect; Last year I found my beautiful, original condition 1978 KZ750 discarded in a garage. Having seldom seen the light of day since she was imported to England from USA during, I think, the early 80s she required only minor repair; battery, starter clutch, tyres and brakes. 27,000 miles, 350 USDollars; no other stats needed. Certainly as much fun as any machine I have owned in over 40 years road riding.

Brent Schapansky
5/5/2009 1:46:45 AM
I'll shout out a halelulea (or whatever) to the end of that article. I traded a wrecked car to a country auto wrecker here in northern Alberta for a '76 KZ750 B1 last year. I also got a '77 KZ650 Four basket case for parts. After about 14 months, the old twin is 90% complete, needs only a set of pipes, a new ignition switch and a new battery and paint for the bodywork. It has the swing-arm and rear, and front end, from the 650 which was a C1 so dual front disks. The 750 has 42K miles on the odo and was said to be a good runner. I fired up the engine sans exhausts, while it was on the bench. It fired up after about 3 cranks of the starter and as expected, was LOUD :) but ran nice. I ditched the stock seat, rusted out pipes and mufflers, rusty spoke wheels (650 gave up nice cast alloys) and horribly uncomfortable stock bars for horribly uncomfortable Clubman bars, a custom seat, shortened the parralel portion of the seat section of the frame by 6 1/2 inches, keeping the stock cowl and rear light mounts and I gotta say, it looks pretty sharp, even in primer AND, it is 97% factory parts, even if only 60% stock. The Lonesome Twin lives on! Brent in Peace River, Alberta, Canada








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