This article was originally published in the July 1973 issue of Motorcyclist.

Performance plus, the Z-1 is the second generation of a whole new breed of motorcycles. Out on the road we found out just how super the 903 is...or isn’t.

Few other machines in the history of motorcycling have captured the interest of readers and riders and writers like the Kawasaki Z-1. Almost before it was available to the public, more magazines, enthusiast and general interest, had written about and photographed the Z-1 than any other new motorcycle in history. More time was spent developing the Z-1 expressly for the American market than any other Oriental mount since the great Japanese motorcycle invasion 15 years ago.

The engine can’t be denied. The four-cylinder dual overhead cam, square engine (66mm bore and stroke) is the strongest motor in mass production today. The powerband runs from 3000 to 9000; a 6000 rpm spread—the broadest in the business. Dependable. Every test, speed attempt and dozens of distance and time records confirm the unparalleled dependability of the engine, It is the fastest of the bikes and recorded a scorching 122 mph in fifth (computed from engine rpm due to speedometer error) across the barren wastes of Nevada. In sheer total engine performance, it is the most shattering of the group.

1973 Kawasaki Z-1
Performance shattering as indicated by honest 122 mph blast across desert. High performance compensated for with 37.5 mpg average and running happiness on low-end fuel.Eric Rickman

Natural smoothness from the monster motor comes inherently from the four-cylinder design. This helps counteract natural imbalances and mass production imperfections. Pleasant to ride it is, velvet smooth it isn't. The Z-1 has a harsh, high-pitched tingle right smack dab in the middle of its cruising range. Between 4000 and 4500 rpm (63 to 71 mph) the engine picks up a caustic harmonic that can get to the rider. Compared with the Honda Four engine it has a high frequency vibration throughout its entire power range enough to oscillate and blur the mirrors. The Kawasaki isn't quite as smooth as the BMW, Norton or Honda and for long distance touring it's slightly more annoying. Long distance discomfort is increased by the waffle-style hand grips that chew into the fleshy part of the rider's hand unless he's wearing padded gloves. Saddle comfort, both solo and two-up, is below the standards of such an up-to-date road burner. The BMW or Guzzi saddle would be a welcome improvement.

Gearbox ratios seemed rather close together considering the superbroad powerband of the Z-1, but are understandable with its performance breeding and modest torque output. Top gear passing placed it slower than the Norton and Trident and tied with the Yamaha. Of course there's always a lower gear to punch if you need it. In town, the enormous clunking going into first and second is something that just seems inherent with all the big Japanese tourers. An unusual complaint from many of the riders was the immovable solidness of the shift lever (when toeing up) of the Z-1 in top gear. Having a slight spring cushion for foot movement would be a comfort aid. The lurch experienced in the morning, when first put into gear, is teeth-gritting, but it's the only way the clutch plates will break their stuck-together seal. Why the large Japanese roadsters don't use a dry clutch like the BMW, Harley or Trident baffles us. It would cure the lurching problem as well as the clutch adjustment variance as the engine gets hot, hotter, then hottest.

Sophistication of the marvelous Z-1 four with its DOHC’s and quartet of carburetors leaves the average shade tree mechanic out in the cold when it comes to tune-up and valve adjustment. Our personal experience verified this and most of the riders expressed disappointment about having to go to the dealer for what used to be a Saturday afternoon task. Involvement of the electrical system usually wouldn’t come to mind. During the concluding days of our test, the Z-1 started blowing fuses. It would happen while the bike was running and cause a severe drop in performance. When stopped, the electric starter wouldn’t work, although we could start it manually. Field-tracing the problem is impossible. Fabulous as the Z-1 electrics are, tracing problems in it is for experts only.

Only the low-geared Trident engine spins faster than the Z-1 in top gear, which led most of the testers to comment that the four sounded “busy” at highway speeds though not distressing. Electric starting is quick, although the engine was the most cold-blooded of the group. Lighting is good, with the Z-1 having the best sealed beam headlight. Instrument placement and ease of understanding operation of the controls is tops. As with most of the others, speedo accuracy is highly optimistic. With all its power and mechanical goings-on, the Kaw was third quietest in the noise test, only louder than BMW and Honda. For such a performance-oriented machine the Z-1 gets good gas mileage (37.5 mpg average) and runs happily on low-cost regular.

1973 Kawasaki Z-1
Monster motor of Z-1 keeps its cool with generous finning of wet sump engine.Eric Rickman

The single biggest complaint about the Kawasaki centered on its choppy riding discomfort due to the rigid suspension. Solo, the shocks are rock stiff, and hardly passable with a passenger aboard. The forks offer no forgiveness to minor road irregularities and clank continually as they “top out” over small bumps and dips. At 546 pounds, it’s still the best in high-speed and mountain road handling of the Japanese bikes.

At first skeptical of the tires, we found them to be a superb match to the machine. However, the rear suffers the same ill as the other Oriental mounts, which is premature wear. On the highway, you’ll stretch getting 3,000 miles from the rear and the huge number 60 chain will fall by the wayside about the same time. Parts for the Z-1 will stagger some buyers. Condensor set, $8.16; throttle cable set, $12.96, and a set of valves is $62.64, more than double Honda’s list.

Our close relationship with the Z-1 since the first of the year has given us more insight to it than most of the other machines and therefore explains our detailing its moderately few faults. We have a total of over 8,000 miles on Z-1’s in the last four months which gave us much more feel and experience with it for both its highlights and faults. Shattering, but controllable power, immaculate construction, engineering excellence in all areas except the driveline and forks, unbeatable durability, sporting appearance, civilized conveniences and the $189 price tag make the Kawasaki Z-1 the best performance sporting buy in motorcycling. It has the potential of being the best all-around road bike ever made. A few more years’ production will tell the story.

Attention to detail and fitting the machine with dozens of small conveniences speak highly of Kawasaki’s devout interest in the success of the Z-1. A super service manual, maintenance specification tags under the saddle, dual helmet locks, an outstanding tool kit, and a convenient registration tray with an inlaid wiring diagram located under the locking seat are conveniences absent in the machinery costing haf again more. And, hopefully, like the Honda Four, the Z-1 will become more of a touring machine as each year goes by.