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Kawasaki Z1 900





Make Model

Kawasaki Z1 900




Air cooled, four stroke, transverse four cylinder, DOHC, 2 valve per cylinder.


Bore x Stroke 66 x 66 mm
Compression Ratio 8.5:1


4x 28mm Mikuni carbs

Ignition  /  Starting

-  /  electric & kick

Max Power

82 hp 59.8 kW @ 8500 rpm

Max Torque

73.5 Nm @ 7000 rpm

Transmission  /  Drive

5 Speed  /  chain
Double tubular steel cradle

Front Suspension

36mm Telescopic forks

Rear Suspension

Dual shock, 5-way preload adjustment

Front Brakes

Single 296mm disc 2 piston caliper

Rear Brakes

200mm drum

Front Tyre

3.25 H19

Rear Tyre

4.00 S18


230 kg

Fuel Capacity 

18 Litres

Consumption  average

48 mp/g

Standing ¼ Mile  

12.3 sec / 112 mp/h

Top Speed

135 mp/h

If one machine summed up the spirit of Seventies super biking, it was Kawasaki's Z1, which burst on to the scene in 1973 and dominated the decade with a performance that put it streets ahead-often literally-of the opposition. The first big 'Zed' was a landmark motorcycle, raising the speed stakes to new heights and establishing a reputation for brute power and reliability that Kawasaki has retained to this day.  The Z1 early story is one of triumph over near disaster. In the fall of 1968, Kawasaki's engineers were dismayed when, with their own plans for a radical four-cylinder 750 well advanced, they were suddenly confronted by Honda's CB750. Kawasaki considered scrapping their project, code-named 'New York Steak' - but, instead, they learnt all they could from the Honda, enlarged their own twin-camshaft engine to 903cc, and returned four years later with the Z1. 

The wait and the extra work were worthwhile, because the Kawasaki was a better bike in almost ever)' way. Its big motor put out 82bhp - 15bhp more than the single-cam Honda, and enough to give a top speed of 130mph. It was smooth, it was tractable and it was almost unburstable. Tuners and racers adopted it in droves, and Z1-based bikes were soon competing successfully at ever)' level from club-racing to the international endurance events.  But there was much more to the Z1 than simply an engine. The bike's rounded styling was striking, its handling was reasonable (though when pushed hard the Kawa could get seriously out of shape), and it was even fairly comfortable despite the high handlebars. The inescapable conclusion when comparing CB750 with Z1 was:

 'The King is dead. Long live the King.' Such was the performance of the Kawasaki Right: Handling was respectable by early-Seventies standards, but the Z1's chassis combination of simple frame, skinny forks and single disc ensured that a rider had to be brave.  that it needed virtually no changes to remain on top when it became the Z900 in 1976; it merely gained a second front disc brake and slightly firmer suspension. A year later came the Z1000, its motor bored out to 1015cc to give even more low-rev smoothness and punch.  The following years saw the big 'Zed' in a variety of guises: Café-racer Z1-R, shaft-drive Z1000ST tourer, and later the fiery red GPz1100 sportster. All were good bikes.

Source of review: Roland Brown

Road Test

But it doesn't stop there, since we can also find beauty in performance. And the Z-1 is probably the most performing production motorcycle on planet Earth. It has enough top speed, acceleration, and braking power to satisfy the most gutsy of heroes. Too, it can handle the tough twisties without a shake, shudder, or snarl.

On top of everything else, Lady Z shows just how foxy she really is when ifs time for manners; in heavy town traffic, touring on the open road, or just firing up in your driveway without disturbing the neighbors late at night It is hush, hush quiet, but the sound evokes attentive respect for the power that surely lurks within.

Development on the project, dubbed, "New York Streak, "started some time back around 1968. Kawasaki was taken by surprise by Honda's intro of their 750, and did a bit of re-evaluating; the result being a late 1972 introduction of the 1973 900 Z-1. While the new "Z" will often find itself compared with Honda's enormously successful 750 Four, there is more of a difference than one would imagine.

The only real similarities in styling (the ones that might make you think it's a Honda at first glance) are the four exhaust pipes and the large size of the overall motorcycle. Otherwise, the Z-1 has a look all its own.

At the front the big Kawasaki is blessed with a new design high speed tire, the Dunlop K 103. The three center ribs are designed to aid stability at the speeds the 903 is capable of. The fender is chrome and has no rods or braces to support it; very clean looking.

Lower fork legs are aluminum and have cast in recesses for the amber side reflectors, a design that will make it rough to remove the lenses. After all, the recesses will still be there. Though the left leg carries the big disc brake and caliper assembly, the right one also has cast on lugs to fit another complete stopping unit. The disc assembly looks to be the only component borrowed from another Kawasaki, the 750 H2.

By not fitting rubber boots to the sliding portion of the forks, Kawasaki has kept the front end very stylish and light looking. So often these rubber boots give a bulky look to many different motorcycles. To keep dirt from ruining the oil seals, rubber wipers snap on the tops of the lower fork legs and maintain a good seal from the elements.

The headlight is a conventionally styled item and its ears contain the front turn indicators. Just above the sealed beam are the instruments, the nicest ones we've seen on any motorcycle. They're streamlined; that is, swept back and shrouded in an extremely pleasing manner, with the speedo on the left and the tach on the right. In between, facing the rider, are the now fairly common warning lights. More important though, is the placement of the ignition switch . . . right in the middle of the instruments where it is easy to reach. The 750 Honda, you'll remember, still has its keyswitch down under the tank a la 1960.

Lighting controls are all at your fingertips near the handgrips. The 900 has its high beam and on/off headlight controls independent of each other, so when you switch to low beam you don't mistakenly turn off the lights; a common occurrence on the 750 Honda.The starter button is just by your right thumb; the kill button just above that.

For as big as the fuel tank is, it doesn't look bulbous or out of place. Its shape, as well as the paint treatment, combine to make the 4.76 gallon unit a thing of beauty. The cap is the flip up type, and requires two hands to pop it open. That might seem a bit of trouble at first, but the first time you see one of the local four year old house apes try it, you'll see why they made it that way. The chances of a kid getting it open and filling your tank with goldfish are slim indeed.

We don't often find a motorcycle seat that not only looks good, but offers the ultimate in riding comfort for both the rider AND passenger. Well, we found one on the Z-1. It's as comfortable as the one found on the BMW machines, but it looks a lot better. And a nice, solid hand hold is awaiting the passenger's grip in the form of a hefty, chromed bar just behind the seat.

Of course a seat so well designed surely must flip up to reveal items that the owner must occasionally get to and, it does. The battery is there, the tool kit, the pop out air filter element, even a little slide out tray that fits in the tail section and holds your owners manual and registration.

Flexible type plastic is used in the snap-on side covers and the upper portion of the rear tail section. Paint on the machine is a metallic brown and orange and, very pleasing.

Since most of the braking force is needed at the front wheel, .a standard drum brake is fitted to the rear. Dunlop makes the 4.00x18 K87 mk 11 tire, fitted to the back wheel.

When you talk about the styling of the Z-1, you can't leave out the engine. Where is class with a capitol "C". Kawasaki has painted the thing black and adorned it with chrome and polished embellishments. The most far-out looking engine ever fitted in a production motorcycle. Fifty-five cubic inches, double overhead cams, and 82 horsepower. Lots of work and research went into this four, and that much more testing.

For the displacement of this engine, it is still fairly narrow. The designers undoubtedly wanted to keep the crank as short as possible for this reason. Though it is short, it is actually nine pieces that are pressed together, and naturally, very strong. And unlike many engines of this size, the crankshaft rides in needle, rather than roller bearings.

In order to eliminate drive train snatch, the engineers came up with a direct primary drive system. The gear teeth for the drive are cut directly on the number four crankshaft counterweight, which eliminates any need for chains or idler gears. And it works.

Compared to the Honda Four, little grab or snatch is present. And, since the big 900 drops or picks up rpms slower than the Honda, it can be ridden more smoothly in traffic.

The two overhead camshafts, an unusual feature on a production type engine, are driven off the center of the crank, by a chain. The chain is a single row type, with no master link, and features an external adjustment for the tension. Another gear on the crankshaft drives the engine oil pump.

When you're ready to push the electric starter, there's no need to find neutral. The starter drives directly to the crank, but not so the kick starter. This one connects up to the clutch, so neutral must be located first. The kick starter will probably only be used when the battery is low or the weather exceptionally cold.

As far as gearboxes go, the one in the new 900 is high on the rating scale. It is a five speed unit, with low gear being down, and the remaining four up, in the pattern. It seems to work faultlessly, and no doubt the strong, eight plate clutch has much to do with it.

Honda's initial problems with their drive chain drew plenty of adverse publicity and forced a recall on thousands of machines. Kawasaki researched this problem carefully, and tried to come up with a chain that not only wouldn't break, but one that would last as long as possible. Drive chain wear on a big, high powered machine is critical.

The final result was what is probably the largest chain ever put on a motorcycle; a 3/4" pitch monster, bigger even than the one that graces the sprockets on the Harley-Davidson Electra Glide. Like the Honda, there is no master link. If you need to change the tire, provisions have been made to make the job possible without too much hassle.

To keep the links moist with lube, a gear driven pump meters the oil of your choice from a small tank under the left side cover. The oil is delivered at the rate of 5cc an hour at an output shaft speed of 1500 rpm. Even with the pump, however, Kawasaki recommends that you lube the chain by hand every three hundred miles, for the longest chain life possible. But, don't expect more than about 5,000 miles per chain with the "Z. " The rear tire will last about the same length of time.

Though economy isn't possible with tires or chains, the big bruiser gets thrifty in the fuel department. 40 miles per gallon can be expected on a normal ride, and the fuel you put in that tank is regular — that's what Kawasaki advises you use.

The 903 even has a smog system, so to speak, the first bike ever to use such a device. Crankcase fumes are shuffled through a canister and eventually back to the carburetors to be reburned. No doubt future legislation will require such devices, and Kawasaki is just that much ahead of the game.

You will find that the 900 is extremely cold blooded, and requires about five minutes of warm up before it will accept throttle turning. Also, it needs a good thousand miles of break in before hard running is done. The Kawasaki people were very definite about this point. So much in fact, that they do not release any test machines to the press unless they have at least 1000 miles on the odometer.

The Z-1 will cruise comfortably at any speed the rider feels he can get away with. At 80, for example, the engine is literally loafing at 5000 rpm. Top speed is much faster than most riders will ever want to go, or even try once. Acceleration is phenomenal, but you don't realize just HOW fast you are going until you look at the speedometer. Then, your heart THUMPS!

It likes to go around corners, though it never lets you forget that it is a big machine, about 540 pounds all fueled up and ready to ride. If you get into trouble, it will be your fault, because the 900 doesn't play tricks like the 750 Triple.

It is everything you've wanted in a big street motorcycle, and once you sample its cadence, you'll see what we mean.

Motorcyclist review

So there you were in 1972, laying low, dodging the draft, tie-dyeing the cat, grooving to your Rod McEwen records, rebelling and protesting but most assuredly not inhaling. You thought that Honda's awesome 750 Four, a bike that had come out the same year man landed on the moon, was about as advanced as motorcycles could get, and then....

Oh what's the use?! I can't write this story--heck, I was only 13 years old, and thought my brother's Bronco 50 was the height of trickness. In those days, the main concern, frankly, was, er, satisfaction. I couldn't get no, probably because I was about 4-foot-2 and 39 pounds with acne and a stutter. (Really, I haven't changed much.) I had about as much chance of getting my grubby paws on a shiny new Z1 as I did of getting my grubby paws on Tracy Coleman the prom queen, which is not to say that certain fantasies weren't entertained about both. All right, I'm lying. Z1 Kawasakis never entered my imagination until a while later.

Meanwhile, Kawasaki was selling the things--at $1895 a copy--like your proverbial hotcakes. The factory cranked the first Z1s out at the rate of 1500 per month, while it gauged the buying public's reaction (already gauged a few years earlier by Honda's 750 and found to be !$!$!). By 1975, Z1B's were being extruded at the rate of 5000 per month.

Why the Z1 was so popular is a question easily answered by looking at its competition--there really wasn't any. Honda's CB750 was the first mass-produced four-cylinder for the masses, but its styling, restrained to begin with, was long-of-tooth by 1973. (Other "open-classers" that year included such dismal relics as the Yamaha TX750 and Triumph Trident.) The Z1, in comparison, was swoopy, stealthy, waspy--check that ducktail rear end, the tank shape, chrome fenders and blacked-out engine. Like Tracy Coleman, it was a simple case of proportion. Everybody's got the same parts; how they're put together makes all the difference.

Having gotten over the initial shock, it was time to delve into the beauty within. You'll note that there are two cams up there--two. (Say, what's a cam?) And look how big it is! 900! Hooo! That's the biggest dang monster. The driveway basketball game always screeched to a halt when Big Kev's Z1 burbled past. Apparently we were looking at the world's first superbike.

By now you must've already heard the story of how the Z1--code-named "New York Steak" for some ridiculous reason or other by Kawasaki--was originally intended to be a 750, and of how Kawasaki brass nearly suffered a corporate coronary when Honda introduced its own 750cc four-cylinder in late 1968. Kawasaki, cornered, had no choice but to make the Z1 even bigger and stronger and tricker than the mighty CB750.

So the Z would have double overhead cams, and they would transmit their meaty motion directly to the valve stems without interference from rockers or pushrods--the way God intended, dangit--and yes, at a nicely square 66 x 66mm, it would displace 903 cubic centimeters.

Inklings of what was to come arrived at Motorcyclist in early 1972, when Editor Bob Greene put down his coffee cup and traveled to Japan to put cheek to seat for the first time, in the tight confines of Kawasaki's dragstrip/testing area, filing this report:

"Weeks of anticipation exploded with a violent twist of the throttle grip as each rider's turn came up, redlining the silky four in gears one through five. Some saw 100, some 110, one 120 mph before the rapidly closing wire fence at the end of the strip occasioned the near-full use of both brakes. An occasional chirp of rubber told that one of the more hungry pressmen had almost overcooked the Steak as he reluctantly backed off the big burner...."

Test units were dispatched to the U.S. in early 1972, here to be flogged by a team of grizzled American Kawasaki employees led by one Bryon Farnsworth. Three Z1s were hammered for 5000 miles around Willow Springs and Talladega Raceways. Willow, nothing then but a track with barbed wire around it, was the first venue.

"Bill Huth [Willow's owner since forever] said he'd stand guard and make sure nobody drove across the track," Farnsworth recalls.

"Talladega was prone to having those heavy thundershowers," he added. "We were down there testing with Gary Nixon, Hurley Wilvert, Paul Smart, some fast Texas guy whose name I can't remember, and three or four hot Japanese riders. [Yvon DuHamel and Art Baumann were there as well.]

"What we were trying to do was just hold the thing wide open through a whole tank of gas. If you could just hold it wide open, you could run right up there against the wall, doing about 140. It'd wobble some, but if you just kept the gas on, it was OK.

"So I sent out one of the Japanese guys. It started to rain one of those big rains, and he pulls in. I was in charge of testing, so I walked over to him to ask, 'What the hell are you doing?'

"'It's raining,'" he says, "'too dangerous.'"

"Bullshit, I said, and jumped on the bike myself. I scared the absolute hell out of myself that day next to that wall. In the rain, it was really dodgy.

"Still, for the amount of power [the engineers] shoehorned into what was really basically an H-1 frame, the thing worked pretty well. I mean, you could feel the head moving in relation to the swingarm pivot whenever you twisted the throttle, but it all worked. Frames then were pretty much all the same; here's where the engine goes, and there's a place for the seat and gas tank," says Farnsworth.

Phase Two of Farnsworth's test consisted of an 8000-mile L.A.-to-Daytona-and-back flog, the same bikes cleverly disguised in Honda CB750 fuel tanks and badges to avoid detection. One young guy in Shreveport, Louisiana, was the only one to see through the Honda facade in the entire journey; "What the hell izzat? That ain't no Honda."

Rear tires were roasted at 6000 miles, and drive chains at half that. Otherwise, everything appeared ready for prime time after teardown back at Kawasaki HQ in California.

Dealers sold out of Z1s immediately, so quickly that Kawasaki employees couldn't even get a Z through the employee discount deal. Aftermarket performance suppliers who'd gotten involved with the CB750 Honda went completely ballistic in cranking out pipes, cams, carburetors, wheels and brakes for the Z1. Those parts encouraged people to ride fast, take lots of chances, and to race. Those races encouraged the competition (after it rocked back off its heels a few years later) to build things like Yamaha XS Elevens, Suzuki GS1000s, Honda CBXs and war that continues to this very day.

The Z1, though, had already exceeded the ex-pectations of its conceivers. From 1973 on, the name "Kawasaki" would no longer be associated with loud, smoky and pipey two-stroke triples, but with big, brutal, powerful--and most important, refined--four-stroke motorcycles.

Source Motorcyclist




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