How Ninjas took over the world. From GPZ900 to ZX-10R

The original GPZ900R of 1984 sired a long and illustrious family of Ninjas that are a huge part of motorcycling today. From the mental ZX-10R to the blistering ZZ-R1400, none of them would have existed without the GPZ900 25 years ago

They have plenty in common, the latest ZX-10R and the GPZ900R, its inspiration from a quarter-century ago. Potent straight-four engines, top-quality chassis, sharp looks, and an unmistakably aggressive presence. What separates them — even more than the 80bhp and almost 50kg in the young gun’s favour — is this: in its day, the GPZ900R wasn’t merely one of the world’s top superbikes. It was the best. By a country mile. In a world of air-cooled, twin-shock monoliths, the original Ninja was a revelation.

What made the Ninja so significant was its liquid-cooled, 16-valve powerplant; a major development from the firm that had been renowned for its eight-valve fours ever since the original Z1 of 1973. But what made the Kawasaki great was a combination of style, new technology and performance that blew away everything else on the road. How good was the original GPZ900R? When I tested one against four of its closest rivals on the Isle of Man in 1984, the Ninja wasn’t just the best bike of the bunch, it was also the favourite of all five riders on the trip. It had won that year’s Production TT, too, ridden by Geoff Johnson.

The GPZ900R was never fazed by competition, not least because in ’84 it was neither the most powerful nor the most high-tech superbike even in Kawasaki’s own range. Its 908cc engine’s 113bhp max was five horses down on the 1,089cc unit of its aircooled, eight-valve sibling the GPZ1100. And the Ninja was far less complex than the 3bhp less powerful Z750 Turbo. But they were dinosaurs.

The streamlined Ninja was the fastest of that trio, around a racetrack and in a straight line too. It instantly established liquid-cooling and four valves per non-turbocharged cylinder as the way to go. Then it proceeded to fend off its supposed replacements. It outlasted both the 1986-model GPZ1000RX (more powerful but less agile and £500 more expensive) and the 137bhp ZX-10 that arrived two years later.

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The Ninja craze

In 1990 Kawasaki finally created a suitably fast and impressive flagship, the ZZ-R1100, to replace it. But even then it refused to die. In that same year the GPZ900R was not retired, but was uprated with thicker forks, 17-inch front wheel, wider rims, fatter tyres and bigger front discs. It had lost the original bike’s anti-dive front end and similarly dated 16-inch front wheel, but its looks and performance were intact. Which, as Suzuki’s GSX-R750 had redefined the super-sports class in ’85, meant that the once all-conquering GPZ had finally been relegated to sports-tourer status.

Kawasaki had tweaked the camchain tensioner and lube system over the years, as well as coming up with a convoluted carb-warming system to prevent the curious problem of its Keihins occasionally freezing. The most cunning wheeze, devised in response to complaints that the engine ran hot, was to modify the temperature gauge — leaving the temperature itself unchanged. Overheating was an occasional problem, as was camshaft pitting, but basically the motor was bulletproof in four-cylinder Kawasaki tradition. By 1991 the 900R’s most important number was not its unchanged 113bhp peak power output but its amazing price of £5,159, identical to the ZZ-R600 rather than the £1,500 more expensive ZZ-R1100.

The 145bhp, ram-air assisted ZZ-R1100 continued a dynasty of ultra-powerful, liquid-cooled Kawasaki fours that led via the ZZ-R1200 to the current ZZR1400. The GPZ900R’s web spread in different directions, too, starting in the mid-Eighties with the GTR1000 tourer and the US-market ZL900 Eliminator cruiser. One step too far was the ’85-model GPZ750R, identical to the 900R apart from smaller-capacity engine, which was outclassed by the GSX-R and Yamaha’s FZ750.

There’s plenty of trademark Ninja fire and toughness in the current ZX-10R, of course. The noise the airbox generates under full thrust on the 10R is the same as the ZX-7R a decade ago, all pent-up anger and aggression. The clean, uncluttered lines are pure Kawasaki, as is the demented straight-line speed and the ability to cover big distances.

The GPZ900R itself was still going strong in this Millennium, being sold in far-Eastern markets including Malaysia with bright yellow paintwork but otherwise almost identical to the A8 model of the early Nineties. And the Ninja lives on here too. More than 3,000 were sold in the UK, where a 500-strong members club remains, run by Wiltshire-based Craig Davies, who can source spares via his web site. That lasting popularity is well deserved. For original impact and lasting performance, few bikes come close to the GPZ900R. Ninja to the core.

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Ninja family tree

Kawasaki Ninjas have a long and illustrious history. Always fast, always stylish and with a fervent following, the watercooled Ninjas are steeped in attitude. And above them all, like a proud parent regarding its offspring of hooligans, sits the GPZ900R.