The GPz900R is not only the most significant Kawasaki of the last 50 years, it is also probably the most influential motorcycle of all over the same period, the machine which set the template for the modern superbike, the longest-lived Kawasaki model ever and the first to be given the iconic ‘Ninja’ moniker.
And that’s just the start.
The GPz900R was also so good it outlived not one but TWO of its supposed successors, dominated the TT, starred in a Hollywood movie and sold more than most manufacturers do in total in a single year. Simply, modern superbikes don’t get any more ‘legendary’.
And all of that was the product of one of the longest and most ambitious development processes in motorcycle history.
By the late 1970s, Kawasaki air-cooled, four cylinder, two valve superbikes such as the Z1000 were overdue a successor. All were derived from 1973’s Z1 900 and Kawasaki’s experience of that bike, when it was beaten to the title of ‘the world’s first four-cylinder 750cc superbike’ by Honda’s 1968 CB750, so forcing its then 750 back to the drawing board, prompted Kawasaki to raise the bar even higher for its successor.
The result would be the 1984 GPz900R Ninja, developed in secret over a full six full years, when most motorcycles require only three.
At its heart was a liquid-cooled, 16-valve, transverse four which, like the Z1, was also 900cc (908, actually), but in every other respect was a monumental advance from not just Kawasaki’s previous air-cooled, eight-valve fours but all its rivals. In 1984 Yamaha and Suzuki were still labouring with their air-cooled two and four-valvers while Honda’s new liquid-cooled VF750 V4s had already proved flawed.
Such a significant engine didn’t happen overnight. Kawasaki first considered a DOHC six akin to its in-development Z1300, before dismissing it for its width and weight. Honda-style V4s and V6s were also proposed, while Kawasaki even looked at upgrading the air-cooled motors used in the likes of its Z1000 (and later GPz750 and 1100s). Ultimately, in 1978, the decision was made to design an all-new motor. The result, six years later, was motorcycling’s first production liquid-cooled, 16-valve, DOHC, inline four.
That liquid-cooled element was crucial: as well as allowing the precise temperature management required for tighter tolerances and higher performance, it also, with the combination of a side-mounted cam-chain, allowed the new motor to be slim, light and compact. At 451mm wide, the new engine was 20% narrower than similar big fours of before.
And that was just the start. Kawasaki’s new flagship was also pioneering in being the first superbike conceived as an integrated ‘whole’ with the new motor used as a ‘stressed member’. This meant the engine was also designed within the diamond steel frame as a centralised mass unit resulting in greatly reduced weight and so aiding handling, acceleration, braking and top speed.
This ‘integrated’ approach also led to another first – the GPz900R’s aerodynamic full fairing, which helped it towards a ground-breaking 150mph+ top speed, while other advances included electronic ignition and a lightweight, box section swing arm.
It wasn’t all pioneering, of course. The GPz’s cycle parts were more conventional. Its monoshock rear suspension was a development of that on the 1983 GPz1100 Uni-Trak, as were the AVDS (Automatic Variable Damping System) forks and six-spoke wheels, although the front was a novel 16-inch design.
While its nickname – Ninja – although a Japanese term, was actually proposed by an American, Kawasaki USA’s director of marketing Mike Vaughan, although it was a battle to get it accepted and only used in America at first.
But the GPz900R Ninja’s legendary status was truly earned after it was launched and by the achievements it afterwards made.
Unveiled at the Paris Show in the autumn of 1983, it had its press launch at Laguna Seca in December before going on sale in early 1984. From the outset it was immediately clear motorcycling had entered a new age.
At that Paris unveiling, although its peak power of 113bhp was actually five LESS than Kawasaki’s aircooled GPz1100, its compact, integrated, lightweight layout prompted its maker to describe it as ‘having the performance of an 1100 and the agility of a 750’. Kawasaki also claimed it was the first superbike capable of 150mph, partly due to its aerodynamic fairing, so setting a benchmark it took rivals years to beat.
While at the GPz900R’s world press launch in California, Kawasaki took the unprecedented move of hiring leading US drag racer Jay ‘Pee Wee’ Gleason to demo the bike’s standing quarter-mile prowess. He promptly set a time of 10.55 seconds – a full two seconds faster than its Z1 predecessor – and the world took notice.
Nor was the new Ninja a one-trick, straightline pony. Around Laguna’s sweeping, high-speed turns, the 900 would easily stay with, and invariably outbrake and outturn, both the GPz1100 and 750 Turbo it was launched alongside.
Other records and ‘claims to fame’ quickly followed. The following May, the GPz900R blitzed the 751-1500cc Production TT with Geoff Johnson leading a 1-2 ahead of Howard Selby. Numerous magazine group tests declared the Kawasaki the new class king. By August, the Ninja was motorcycling’s hottest ticket with lines of red Kawasakis queuing up outside dealers for their B-plate release and, at year’s end, the GPz900R was also, almost inevitably, voted MCN Machine of the Year.
But the GPz900R’s biggest claim to fame was that it wasn’t ‘just’ the machine of 1984, it was that it reigned for years to come and inspired a whole new class of liquid-cooled, 16-valve, transverse four superbikes
When, two years later, Top Gun became THE summer blockbuster movie, it was almost inevitable the GPz was chosen as the bike its motorcycle-mad star, Tom Cruise, would ride.
When updated by the larger, more powerful GPZ1000RX in 1986 then 137bhp ZX-10 two years after that, the GPz900R remained better than and outlived both, surviving in Kawasaki’s UK range until 1993, with its engine architecture forming the basis of world-beaters such as the ZZ-R1100.
When the GPz900R was finally replaced in the UK, by the 1994 ZX-9R, it was no surprise that it, too, was a 900 Ninja – its legend had been fully cemented by then after all.
And when the GPz900R finally went out of production after a full 19 years, a total of over 70,000 had been built, which is also partly why it’s not quite the collectable classic its achievements probably deserve – there’s simply too many of them to be considered special.
Instead, the GPz900R’s legacy is probably the whole Ninja dynasty, the term applied to all Kawasaki sportsbikes since, and, even bigger than that, its faired, compact, liquid-cooled, 16v, transverse four with monoshock suspension layout, which became the template for all Japanese superbikes for the next 30 years.
For that, and much more, the Kawasaki GPz900R is a legend.
