The motorcycle fast-tracked in a month that changed motorcycling

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With the recent advent of the 50th Anniversary Kawasaki Z line, we thought a look back at the makings of this iconic motorcycle might be in order. Our friends at the Throttlestop Museum in Elkhart Lake, Wisconsin have a pristine original Z1 900, and some fascinating details about it’s remarkable, desperate development that arguably produced the world’s first “superbike”. If you’re a fan of 1960s-70s motorcycles, this story will fascinate you. If you’re not, you just might become one after this tale.

In 1967, Kawasaki instructed a team of its best engineers in Akashi, Japan to develop a program centered around a large capacity, four-cylinder four-stroke motorcycle with an engine size of 750cc. Kawasaki had been looking east, seeing a rise in American riders and their love for big motors with big speed. Led by Gyoichi ‘Ben’ Inamura, they were determined to be first to bring a competitor to market. This team set to work and birthed the “N600” project, codenamed “New York Steak.”

One year later in 1968, following the Tokyo Motorcycle Show release of the Honda CB750-4 motorcycle, the brain trust at Kawasaki was stunned. Honda had beaten them to the punch. A new directive was given- raise the engine size to 900cc and make more power than Honda. The N600 project was suspended and years passed creating a gaping hole in the market for Kawasaki while Honda saw sales of their CB750 explode. In March of 1971 Norimasa ‘Ken’ Tada took control of the Z1 project’s bike design, and was given one month (!) to design what would become the Kawasaki Z1 900 Super Four. KHI (Kawasaki Heavy Industries) planned production for 1972, so the pressure was on engine design chief Ben Inamura and Sam Tanegashima, the product planning manager to produce a workable design.

After getting KMC (the American-based Kawasaki Motors Corp.) to sign off on the bike design, the R&D team got to work. Kawasaki had their sights set on making a splash in the U.S. so they sent two bikes to test in America. Dressed in Honda colors and badging, the pair of prototype Kawasakis (known as V1s at the time) set out from Los Angeles on a trip to Daytona and back with a few stops, one being Talladega Raceway in Alabama. In early 1972 by the end of testing, the V1 bikes were shipped back to Japan where they underwent further testing and modification. Surprisingly, the only problematic area identified was excessive chain wear, an easy remedy for Kawasaki’s design team.

As the V1 name was dropped, the frames stamped with Z1 (“Z” denoting the ultimate), and the bikes readied for production, a final decision on the color scheme was made. Known as “Jaffa”, the now iconic Candy Brown and Orange was one color option while the other offered was Candy Yellow and Green. One of the only other style changes was the removal of the Kawasaki branding on the points cover, being replaced with “DOHC”. The competitors from Honda were still using SOHC engines in their bikes. The production Z1 was then released in a worldwide press preview in June of 1972. Following the media debut, the decision was made to ramp up production from the slow pace that had already been happening for months by this time.

The official world release in September of 1972 at the Cologne Motorcycle Show in Germany was only weeks before the bike would make its parade laps around Amaroo Park during the Castrol 6 Hour Endurance Race. That race was the last ever won by a two-stroke motorbike. Winning its races until 1976, Kawasaki had created a motorsport legend in the Z1. It was a monster for its time. Owners were taking their bone-stock production bikes, running 12.0 to 12.2 quarter-mile times and throttling them up to 132 mph. All of that with a claimed 82 hp and 54.2 ft. lbs. at 8500 redline being pushed to the pavement. Kawasaki America went further, hopping up three Z1s and breaking 52 FIM and AMA records across three days at Daytona Speedway. The bike won 1973 “Motorcycle of the Year” honors in MCN. Kawasaki had a runaway winner.

With dominating success in motorcycling and holding multiple records over its rivals, there is little wonder why the “New York Steak” codenamed Z1 project sold so well with Americans and across the world. Numbers have been lost over time of the original production and sales figures, but one thing is certain- the Z1 900 Super Four took the world by storm. Motorcycle fans visiting the Throttlestop Motorcycle Museum in Elkhart Lake, Wisconsin this year can see one of the absolute best examples of this bike on display in person or by viewing the virtual museum at throttlestopmuseum.com anytime.

To gain access to the Virtual Museum, click on the link provided above, enter your email, and an entrance code will be emailed to you free of charge.

*photos and info provided by The Throttlestop Museum.

An early promotional brochure by Kawasaki.