Retrospective: Kawasaki KZ750-E: 1980 – 1982

(This Retrospective article was featured in the July 2012 issue of Rider Magazine)

Story and photography by Clement Salvadori
Year/Model: 1981 Kawasaki KZ750-E
Owner: Franco Teti, Los Osos, California

Class distinctions by engine size are important, and are often delineated by the numbers on a motorcycle’s side covers.

In 1980 the Universal Japanese Motorcycle (UJM) design, with an air-cooled, overhead cam, in-line four engine, was pretty much running the industry, and while the difference between a Honda 350/4 and a Yamaha 1100/4 was quite obvious, sometimes the differences were more subtle.

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Kawasaki had never been one to follow the crowd. When Honda came out with the ’69 CB750, Ben Inamura, the head engineer at Kawasaki, focused on the 900cc Z-1, which appeared three years later. And then he developed the KZ650/4, with a bore and stroke of 62 by 54mm, for 652cc total. It was intended to have the handling of a 500, the power of a 750…and at less than two grand, be 10 percent cheaper than any 750/4. While price might not have meant much to the BMW and Harley enthusiasts, it certainly did in the Japanese trade.

The 650 worked for a couple of years, with the aftermarket helping things along by offering all sorts of hop-up equipment. But by 1979 the 750 class was by far the most popular, and 100cc was a lot to give away, so Inamura decided that he was going to have to go 750. This was to be no big redesign—no 16-valve heads, no new chassis—the KZ750 would simply be a bigger, better KZ650.

1981 Kawasaki KZ750-E.
1981 Kawasaki KZ750-E.

Just to clarify things, in 1980 Kawasaki had two very different KZ750s—the KZ750-G parallel twin, the engine of which had been on the market since 1976 (Retrospective, December 1996), and the new in-line four, known by the postfix E.

Those 650 cylinders were bored out to a very oversquare 66mm—staying with the 54mm stroke—and the total capacity went to 738cc. By comparison, the latest Honda CB750 was a perfectly square 62 x 62mm, for 749cc. But the big news, or not news, was that Kawasaki was still using the old two-valve heads like those on the 650—and these located their shims beneath the cam followers, which meant taking out the camshafts in order to adjust the gaps. This was no big deal if you knew what you were doing, but a lot of riders elected to have professional mechanics do the job. Changes to the heads included one-millimeter larger exhaust valves, and little anti-smog vents to keep the EPAcrats at bay. This minimalist trick allowed oxygen to flow into the combustion chamber and mix with any unexploded hydrocarbons, creating carbon dioxide that was on the approved list of emissions.

1981 Kawasaki KZ750-E.
1981 Kawasaki KZ750-E.

This anti-pollutant gizmo did not seem to harm performance. The KZ650 knocked out close to 50 horsepower, and adding less than 90cc made the dynamometer show more than 60 horses at the rear wheel, with peak ponies coming at 9,500 rpm. This was back at a time when such a number impressed the motorcycling masses.
The major changes, other than the bore-out, were the

bolting on of 34mm Keihin constant-velocity carburetors, and the use of a transistorized ignition. An interesting tidbit is that this new four-banger was first introduced in South Africa, a relatively small market, but obviously with the intent of allowing the bike to be consumer-tested before releasing it to the United States and Europe. Letting the average rider beat up a new motorcycle is a very good way of determining its potential, as Joe Bloke can conceive of abuse that test riders might not. Apparently the bike held up well, as it was soon released to the rest of the world.

1981 Kawasaki KZ750-E.
1981 Kawasaki KZ750-E.

Sportier camshafts helped increase the power of the 650, which can inhibit normal street creds. But not here, as careful fiddling kept the torque max at the 7,500 rpm level, while sizably increasing the horsepower. Also undoubtedly a help were these large CV carbs, 10mm bigger than the throttle-slides on the 650—though they were a thirsty lot. Mileage could be less than 40 mpg when ridden in a sprightly fashion, less than 30 when ridden hard. If economy was on the rider’s mind, he could buy the KZ440 twin.

Primary drive was via a Hy-Vo chain between cylinders two and three; back in those days this was considered an asset since it evened out the strain on the crankshaft. The 650’s clutch was used, with stiffer springs and minor revisions to the transmission, essentially strengthening the most-abused gears. And the final-drive chain went from a 530 to a 630. But the total weight of the bike went down a couple of pounds…brilliant. Curb weight was a shade under 500 pounds.

1981 Kawasaki KZ750-E.
1981 Kawasaki KZ750-E.

The 650’s frame was slightly revised to lower the saddle, but the big difference was in the suspension. An air-adjustable Kayaba fork provided almost six inches of travel, with the firmness up to the rider. Angle was 27 degrees, trail 4.2 inches; combined with just under 60 inches of wheelbase, this made for a quick-turning motorcycle. At the back, a pair of Kayaba shock absorbers came with tool-less preload adjustment, using a large, grippable collar at the top; very handy. These allowed four inches of axle travel. Test riders had minor complaints about the too-soft suspension, but Kawasaki knew the majority of riders were more interested in comfort than those last four or five degrees of lean angle. And the racing-inclined could make their own modifications.

Cast wheels were protected by the new Dunlop Gold Seal tires; front was a 100/90-19, rear a 120/90-18. Triple 10.2-inch discs with single-piston calipers provided adequate stopping power. Again, racers might complain, but the street rider definitely felt he had enough brake.

Throw a leg over the saddle and settle in. Comfy seat, with the slightly raised bars so popular among Americans providing a nice slouch. Ignition on, push the button and the two mufflers kept the noise muted. These were the same mufflers as found on the 650.

1981 Kawasaki KZ750-E.
1981 Kawasaki KZ750-E.

Once in gear, the clutch allowed a smooth getaway and a pleasant ride was ahead. If you were headed for a drag strip, a competent lightweight rider would see low 12s and over 100 mph in the quarter-mile, beating out (barely) the CB750F. But the prices of the two were now pretty equal, with the KZ at $2,750, the CB at $2,850. You pays your money and you takes your choice.

Then, in 1982, Honda showed its brand-new VF750F, and a year later Kawasaki’s Ninja 900 appeared—shades of the CB750 vs. Z-1 900. Does history repeat itself?

1981 Kawasaki KZ750-E.
1981 Kawasaki KZ750-E.

27 COMMENTS

  1. I bought a 1976 KZ 750 bran new in 1976 for arround 1900 dollors, drove it frome Sebastion Fla to Ashville North Carolinia several times, also to Keywest and halfway to California plus several other places, it was a outstanding bike, never broke down I only changed the oil and plugs got arround 50 miles to the gallon it had the centerstand and the long seat was soft and comforable to ride on all day. Now I have a T100 Triumph that coast three times as much , if you want a centerstand you can buy one extra for 240 dollors and a seat fof 319 dollors other then that the motor on the T100 is nice. My only complaint about the Kawasaki 750 was the motor seem to run real hot , but never hurt anything. All the bikes now want to put a real low seat height and thats crazy . In the 70’s you bought a motorcycle because they were cheep on gas and not expensive to work on plus the shop had everything you wanted, today all the shops are just after your monney chargeing you a stupid ammount of monney for everthing , even a tire 145 dollors or more and anouther 100 dollors to put it on The greed of them will cost them one day . I could go on and on but I’le stop it here Have a nice day Mike.

    • I bought a ’80 ltd 750 twin with 11k miles for $900..every idiot who had it left their marks, not so deep as the engine tho’..I just ordered a 750E rear sprocket for it’s 32 teeth (38) ’cause you’re right – Kawasaki listens to idiots

  2. Does anyone know anything about the KZ750E with driveshaft. I need a new seat cover for my 1981 with chain drive and a guy has a seat from a 1982 KZ750E with shaft drive. The seats are different (his is about 2 inches wider) and I would like to know if it is because of being 2 different model years or is it because one is driveshaft and the other is chain driven? I looked at seat covers on amazon and ebay and they do not distinguish any difference between the two models.

    • Ken,
      E-bay and Z-1 Enteprise should be able to help with the seat cover. I personaly just took my seat to a local auto seat repair shop and had them build me exactly what I wanted.

      Best of luck.

  3. Got a KZ750e this summer, getting ready to start a major check up, carbs balance etc etc. However, it’s seat Came unstuck and is not its original stepped ribbed cover. Anyone know where I can get one for it?….. Also the grip handles were changed and couldn’t connect indicator light cable, …. Can the original handle bars be still found?

    APPRECIATE ANYONE BOTHERING TO ANSWER,

    THANKS,
    KEN

  4. ken the number on my bike is kz750 BE-037341 ITS A HARDTAIL IN A CHOPPER FRAME CAN U SEND A PIC OF YOUR KZ SILAR AT ALL? NUMBER SIMILAR? IF I DECIDE TO PART IT ILL SAVE THE BARS THX LANI

  5. HAVE A 1981 K-Z 750, 36 YEARS NOW. G-R-E-A-T, I TAP AGAIN HERE, GREAT motorcycle. THE BIKES OF TODAY???? ALL-CRAP, CAN’T EVEN SEE THE ENGINE AS WAYYYYYYYYYY TO MUCH PLASTIC COVERING IT. IF YOU HAVE A K-Z-75O, 1981-2, KEEP-IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

  6. HI, I’M BACK. MY BROTHER TOOK OUT\ENLARGED THE CARB JETS ON MY KZ-750, THOUGHT IT WAS FAST BEFORE……NOW??? it’ll keep up with ANY 1000 C.C. BIKE…………………E-A-S-Y…………..

  7. Got a candy apple red kz750. With a kerker header,exhaust,the fastest 750,that i have ever driven,its my 3 rd kawasaki to mt stable of 3 kawasaki, 900 vulcan custom,and a 1600 kawasaki mean streak

  8. I bought a beautiful red KZ750 spring of ’81. Lots of snow and rain in Colorado that year, and froze my ass off. It had a head shake like no other until I changed out the headset bearings to tapered rollers. Rode it out to Cali and up Hwy 1 when there was little to no traffic. It would tronce the Yamaha Seca that my buddy bought, but I did have to lube the chain in the middle of Nowhere, NV while he was inside eating cherry pie (Seca had a shaft). Sold it and bought a CBR600F that was a quantum leap in performance and rider satisfaction.

  9. Hey just thought I’d chime in. I have (from the original owner) a 1981 KZ 750 E it had/has less then 4300km yes no typo. All original including the tires (and likely the air in them) from 1981. Stored in a heated garage almost all it’s life I believe. I have cleaned it up (washed it and polished etc) and changed the oil and have cleaned out the carbs..oh and YES..new battery (old one just flat..imagine that after almost 40 years!!) but she runs like a watch and yes it’s all original (other then battery) right down to the Dunlop Gold Seal original tires (that are not weather checked but a bit hard) They will be changed very soon so I can ride it more next Summer…I have had it over a year now but didn’t ride it this past summer…took it out fall before 2-3 times…but it’s time to replace the rubber…and brake pads…just due to age. All fluids were changed of course before I had it up and running..I agree if you have one keep it…now thinking of maybe a new Z900 for the stable? If they made a NEW KZ I bet many would jump on it too!!!
    Thanks for reading…and posting.

  10. have an 81 750/4 E1………gonna be 40 in 2 years…runs great…all orig..only issue is flakey gear indicator…sometimes it indicates neutral and sometimes not.Worth more to me than its little cash on market

  11. Hi all, got myself a neat kz750e1 (1980). she runs fine, drips a bit of oil here and there but what did i expect. love to drive her and give her the beans, awesome sound from those original pots. As this is my first bike, i’m still kind of green. What mechanical/maintenance things do you guys check often? i’ve changed the brakes and pads, replaced all fluids etc. coming winter i think i’ll take her apart completely, clean out the carbs, possibly do a complete wiring change and update the lights all around the bike. A new seat too (all anchoring points broke off XD). any tips, tricks, places where i can buy great stuff?
    thanks,
    Joey

  12. I’ve had a 1980 K750E for 3 years down here in Oz. Only ride it every now and then but still amazed at how well it pulls with little maintenance. Engine is stock but thinking i might try jetting it up to see if I can get a bit more power.

  13. Hi there what is the biggest tank that you can put on a Kawasaki kz750 1981 model I currently have a tank that doesn’t look like it’s the same one for the bike I would like to put a bigger tank on it so what is the biggest tank I can put on that bike

  14. IMPORTANT SAFETY NOTE
    You can skip over all this, but read my comment about brakes at the end.

    KZ750 THE RACER
    Bought and road raced a 1980 kz750 for 2 years in the AFM, at Sears Point. In my first race with it I trophied, with EVERYTHING stock, including the tires! However after one race the EOM tires turned slippery. Google ‘Roger Hagie and the Ontario 6hour’ and you will see that the KZ650-KZ750 was a giant killer on long tracks, not just twisty Sears Point. 550 & 750 Kawasakis owned Sears Point the the early 80s.

    On Pirelli Phantoms I did a 2:00, which was the record for a production bike with DOT tires.
    But things were changing quickly. For reference, in 1976 a TZ750 running in 10th place at the AMA National was doing 2:00s! In 1981 the 550 GPZs were over a second faster. And by 1986 250 Ninjas were as fast as a KZ750E1. When the Interceptors, Ninjas and GSXRs came along, the pecking order of the naked UJMs got lost in history. However the KZ750E1 was truly remarkable in its day. But nobody buys an old KZ750 to blow off other bikes, so read on.

    KZ750 THE STREET BIKE
    After the race track I used my bike for canyon riding and commuting, putting on 125,000 miles. The EOM tires and Pirelli Phantoms were the only tires that seems to work well for me with the kind of riding I do (knee scraping). But the general demeanor of the engine made the bike a pleasure.

    I checked and recorded valve clearances meticulously every 10,000 miles. In the first 105,000 miles my valve clearances never changed. Carburation was always spot on. So don’t fiddle with the cards or the valves!! So what should you do? ALMOST NOTHING. Okay, I hosed my bike down 3 times during the 15 years I rode it.

    The early KZ750 had a cam chain tensioner recall. The swing arm pivot should be kept lubed and checked for wear. You might want to upgrade to conical steering head bears. Again, look at my comments at the very end about brakes.

    After racing I put back in the EOM spark plugs. Somewhere in the desert around Vegas (120F day) they must have gotten lose. (they tell you not to reuse and re-torque spark plugs!) Thousands of miles later I notice a rattling engine noise. The sparks plugs are shaking and about to come out of their holes. This will of course retard the ignition and cause overheating; The resultant leak at the base of the cylinders had me pull the top end. There was severe cylinder wear. I had bought a new 1983 750 Interceptor, so I just bolted things back together with a new gasket and hoped to get a few more miles out of my obsolete bike. 110,000 miles later it is still running fine and not using oil. I cannot explain this.

    The starter motor clutch burned out at 90,000 miles. I bump started it the last 35,000 miles. It helps to be 6’5″. It never failed to start! Don’t touch those carbs, they come perfect from the factory.

    A weird electrical problem retired my bike. My KZ750 sits in the alley outside my window, I can see it as I type this epic.

    Kawasaki gave a KZ750 to a magazine and said run it for 10,000 miles. don’t do anything but add gas. It survived in spite of a very loose chain. Motorcyclist listed it as the most reliable/bullet-proof motorcycle. I believe it.

    A KZ650 or KZ750 with under 30,000 miles is still in its youth.

    THE BRAKES!
    The OEM front pads have a huge copper content. They work very well, but were very expensive to replace. And they score up the rotors big time. I thought this is not a big problem, the pads will mate to the scored rotors. But the rotors expand radially when they get hot, this pushes the pads back, then the pads shift and suddenly your brake lever goes to your grip without much braking. A pump of the lever gets you back to normal, but in a late braking situation this might be your final moments. So have your rotors replaced if they score up.

    • Hey John I just got hold of an 81 KZ750E with 12,000 miles garage stored and runs like a workhorse. love your review, dint know this thing could do 12’s on the track. loving this bike

  15. Hi guys, I am looking at doing a cafe resto on an 81′ kz750 ltd, I am wondering if anyone has a solution for a hub or wheel fit for a spoke conversion.
    Thanks

  16. I just bought a 1982 650 CSR with 13,000 miles for $1500. Everythings original except redone carbs and new tires. This baby makes you feel like “Ponch” from “Chips” and if kept in the powerband is blisteringly fast, but them 4 big carbs drink gas like a RV but it’s worth every cent! Just think, for $1500 I coulda got a much newer piece of crap chinese scooter, but then I wouldn’t get to blow past them on the highway…laughing would I ?………~ grin~

  17. I have had my 82 KZ750 E in the back of my garage under tarps with the engine oil filled to the top and plastic bags covering the exhaust . I purchased it new and put 14 k on it before storing it. It still looks new but requires some TLC. to resurrect. Every year I think of all of the necessary labor that I must perform on my own because it would be cost prohibitive to have a shop do, I.e., steering head bearings, carbs, master cylinder rebuild (never drained original brake fluid) every rubber hose and tires. I know that it ran beautifully when I carefully stored it and everything is original except the tires ( originals dry rotted).

    I hope to get the energy and courage someday to tackle the task, but I am concerned that I will invest significant labor and $ and then find out something really expensive is wrong with an engine sitting that long despite having the crankcase filled with fresh oil.

    Any advice or vote of confidence for resurrection?

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