The Legendary Kawasaki Z1

There's really no argument about the Kawasaki Z1's place in moto history. From the instant the root beer-and-orange machine exploded onto the scene in late 1972—redefining streetbike performance overnight—to this very day, the 903cc Z1 remains in many ways the King of Motorcycles. Very much like Honda's revolutionary 750 Four, the Kawasaki Z1 is held in the highest esteem by enthusiasts and historians everywhere.

Of course, the Z1's connection with Honda and the CB750 is a strong one. While the superb 750 Four came first, it was soon vanquished by the functionally excellent and more powerful Z1—frustrating Honda fans for a decade or more afterward. As weird as it sounds, there's truth to the statement that the CB750 actually caused the development of the 903cc Z1, which arrived in 1973, five years after the CB750 debuted at the 1968 Tokyo Motor Show.

The irony here is as gooey as well-set-up chain lube, but the story goes something like this: Like Honda, Kawasaki was busy developing a 750cc four-stroke four in the latter 1960s—right alongside, coincidentally, its bare-knuckled 500cc H1 triple. Kawasaki was obviously a two-stroke company at the time (the 650cc W2 excepted), though it did have a dollop of four-stroke expertise within its walls to call on, having purchased in ’63 a well-established company called Meguro, which had plenty of four-stroke design chops.

The move toward four-strokes made sense for Kawasaki, as it, like the other Japanese makers, knew things were changing on several fronts. Customer tastes—larger and more luxurious bikes were more in vogue, especially in the US—and stricter emissions laws were two of the most important. Within a handful of years, Kawasaki knew its buzzy and loud two-stroke streetbikes, as fast and emotionally stimulating as they were, would be outdated. It also knew its bikes would have to improve functionally and not just rip down the street—or dragstrip—like bats out of hell.

“Before the Z1,” said Z1 development team member Sam Tanegashima on the subject of all-around function in Micky Hesse’s book Z1 Kawasaki, “Kawasaki had developed several very fast motorcycles like the A7, H1, and H2. It was not sure if we were selling engine/horsepower or motorcycle. From the very beginning of Z1 development we made sure to develop one piece of motorcycle, not independent engine or chassis designing.”

In late 1968, as Kawasaki was approaching the point where it would green-light production-parts manufacture of the four-stroke 750 it was developing for the 1970 model year, Honda shocked the world with the surprise debut of its CB750 at that October’s Tokyo Motor Show. The news was devastating to Kawasaki, which understood all too well that releasing its own 750 would likely be seen as copycatting even if the bike was as functionally good as the Honda. And if it wasn’t? Well, that’d be a death sentence for the bike and certainly a black eye for the company.

Other considerations led to pulling the 750cc plug too. During development in ’67, the three slightly different prototype engines they’d built were proving seriously fragile. “The testing done in Japan at the Yatabe circuit,” remembers Kawasaki man Don Graves, “proved that the engines they’d built were not dependable. When the original push from the US asked for a four-cylinder four-stroke machine, Mr. Hamawaki had pushed for a talented engineer from Kawasaki’s aircraft division to be brought in, a Mr. Otsuki, I believe. After all three engines blew up, ‘HP’ [Otsuki’s nickname] began asking for a larger, better engine, hence the 903.”

We can only presume that the discussion of a larger-displacement machine happened right around the time of the CB750’s launch. Regardless of when or who, we know that it happened and set in motion a new round of sketches, clay models, and running prototypes, all of which culminated in the release of the mighty Z1 four years later, in late 1972.

Why build such a motorcycle? Cycle’s Z1 road test in the November 1972 issue, which quoted Kawasaki’s General Manager T. Yamada, read like this: “Kawasaki wanted to build, in their words, the King Motorcycle, a bike beside which the finest motorcycles in the world would shrivel in comparison…a bike that would leave a hot and smoking scar across the face of the sport.” Yamada admitted that you just couldn’t do that with a two-stroke engine. “In the first place, Yamada said, the King Motorcycle must have an engine that sounds right.”

Kawasaki was maturing as a motorcycle company, paying attention to more than just pure power. “No less important,” said Yamada in the Cycle interview, “is the way the engine looks. Who could imagine a King Motorcycle with an engine that looked like a two-stroke engine looks, all crankcases and cooling fins? The King…has to have an engine that looks impressive.”

Still, like the ill-fated 750, the 903cc Z1 project had plenty of headaches along the way and early on was nothing at all like the refined production bike that debuted in late ’72. “It was awful at first,” remembers Kawasaki man Bryon Farnsworth, who was recruited from Cycle magazine in ’71 to become the senior US test rider for Z1 development. “I was the first [American] to ride the Z1 and the only American to go over to Japan to test it. We’d scheduled time at the high-speed, banked-oval Yatabe test course, but it was booked when we arrived, so we did some testing in a big parking lot, with cones. That sucked, but at least we got to ride. The thing dragged its mufflers right away, and I could tell, even at those slower speeds, that the engine, chassis, and suspension were in need of help. At that point, I think they were still in the H1 frame of mind, where the chassis didn’t matter much and it was all about straight-line speed. And with the Z1, you had this great, big, powerful, and heavy engine sitting there, twisting everything into a knot. I told them it was a rakuta, which is water buffalo in Japanese!”

Farnsworth made several trips to Japan in those early days, one lasting nearly two months, and little by little, the prototypes got better. “After the Yatabe experience,” he says, “I insisted we go to a real track, and we were able to get some time at the Tsukuba circuit. We made some progress there, and it helped once the updated prototypes got to the US later in the development cycle.”

The team tested over several months in the US, from Southern California to Florida and several spots in between. Farnsworth gathered a host of riders to participate, including Gary Nixon, Paul Smart, and Hurley Wilvert, all who flogged the bikes mercilessly. The prototypes were run at the racetrack and on the road, and during one trip from Los Angeles to Daytona and back, the bikes had big Honda stickers on the tanks to keep public curiosity to a minimum. At Talladega Superspeedway, which Kawasaki rented for an entire month, the bikes were run at full throttle until they ran out of fuel—and then refilled and run again until empty. “Riders were doing about 140 miles per hour,” Farnsworth remembers with a smile. “The bikes still wiggled at speed but only if you let off. If you had the balls and held it wide open, it was okay.”

Despite a few niggles and that top-speed shimmy, the Z1 had become a pretty solid motorcycle during those 18 or so months of prototype testing. “I think my input early on, when the Z1 was really rough, was a key factor in the model’s success,” Farnsworth says. “We really did try to make the bike bulletproof for the American rider. I’m really proud of that.”

As pre-production bikes (those hand-built with production parts) began to become available in mid 1972 for final performance and emissions testing, the Z1 team felt reasonably comfortable with their efforts. Farnsworth felt similarly and came up with an idea that would help launch the bike to the press and public in dramatic fashion. “I suggested we go to Daytona and set all the world FIM and AMA 24-hour endurance records,” Farnsworth says. “Thankfully, upper management agreed, and we put together a plan. We knew from all the high-speed testing at Talladega that the production Z1 would easily smash all the records at the time, as it would run at 140 miles per hour all day long.” Then, the record for a 24-hour average was just 90.1 mph.

Farnsworth’s full-factory assault team, made up of Gary Nixon, Yvon Duhamel, and several US magazine editors, including Motorcyclist’s Art Friedman and Cycle’s Cook Neilson, arrived at the Speedway to see what the new Z1 could do. Turned out it could do a lot, slaughtering the record by almost 20 mph with a 24-hour average of 109.64 mph for 2,631 miles. A special one-off Z1 tuned by Yoshimura and ridden by Yvon Duhamel set a new record of 160.288 mph for one lap.

“It was a bit of a gamble because a lot of things could have gone wrong,” Farnsworth remembers. “But it really paid off, especially by using credible members of the press—who’d all write about it—and also current AMA racers to set the records. Folks could see the bike was crazy fast but also bulletproof too. It was wild going into the banking at 140 mph; it looked like a wall as you approached it, and holding the throttle open and not backing off took some doing!”

Meanwhile, Z1s began flying out of Kawasaki showrooms, with hugely positive magazine reports helping keep the momentum going. Before late ’72, when production Z1s first became available, Honda’s CB750 and Kawasaki’s own 500cc H1 owned the open class. And while the appearance of the 750cc H2 in late ’71 added to the two-stroke momentum Kawasaki had generated, the launch and appearance of the comfortable, refined, smooth, quiet, and downright ass-kicking Z1 changed the conversation overnight. Here was a bike that seemingly did it all, from around-town runner to comfy tourer to dragstrip demon to back-road burner. In other words, a superbike. The first of its kind, in fact.

“The Kawasaki 903 Z1 is the most modern motorcycle in the world,” wrote Cycle in its November 1972 issue. “It is also the fastest. It is above all the first of a new generation of bikes…a generation which will come close to being within reason all things to all people, capable of nattering down quiet country roads packing double one minute and rotating the Earth with incomprehensible acceleration the next.”

Al Arbor, who ran Kawasaki East in Nashua, New Hampshire, for nearly two decades, says the Z1 was key in building Kawasaki’s reputation in the US. “The Z1 really did do everything,” he says. “And a lot of guys used that to their advantage, telling their wives that the bike would be for them to travel on. Once they got permission to buy it, it was often a different story! The thing was fast and comfortable and nearly indestructible; we dragraced them for years, and our shop held grudge-match events for customers at a nearby dragstrip on Wednesday nights. Those were good years.”

It’s fitting that we honor Kawasaki’s legendary Z1 in 2016, this year being the 40th anniversary of Superbike racing in America and the world. After all, the Z1 really was the very first superbike—on the street, for sure, as there was literally nothing like it on the road. But also on the racetrack, as the Z1 was, in the Open Production classes that eventually morphed into AMA Superbike, the bike to beat.

A couple of fun Z1 facts before we leave you: According to Kawasaki’s website, the Z1 name came from Z being the last letter of the alphabet, which represented the most extreme position. And the number 1 stood for “number one” in the world. Another bit of irony regarding the Honda/Kawasaki connection is the CBR900RR of 1993, which debuted 20 years after the Z1’s introduction. The 900RR was originally a 750 and got all the way to the late-prototype stage before Honda changed course, feeling a 900 would have more market impact. Like Kawasaki’s decision to move up the displacement ladder and build the Z1, Honda made a smart move.

In the end, the Z1 was nothing less than a revelation—a motorcycle that shined a bright-orange spotlight on the future of motorcycling, a direction every other manufacturer ignored at its peril. That direction was performance oriented, for sure, but it wasn’t a narrow-focus sort of performance, as represented by, say, the Mach III. It was balanced performance—speed and power, for sure, but also comfort, quietness, smoothness, and civility. The fact it was as reliable as a hammer didn’t hurt either. As one magazine wrote about the Z1: “Every inch a king…”