According to the encyclopedia, a Ninja (or Shinobi) is a Japanese secret agent from feudal times. While the Samurai were upper class, noble warriors concerned with chivalry and honor, the Ninja were from the lower orders and signed up to do all the dirty work. Assassinations, spying, secret missions: the Ninja did it all.
The term became 'cool' in the west after World War II. Japan had made a pretty good showing of itself in terms of sheer violent savagery, and a certain admiration developed. That, together with the long-established reputation of Japanese martial arts and the mystique of a closed society meant Ninjas became the scary comic-book characters we know today.
So, silent killers, enlisted from the lower orders and used for nefarious underworld deeds. What on earth made Kawasaki choose it as a name for its sportbikes?
Back in the 1970s, Kawasaki was doing very well in the big bike market. Its 900cc Z1 appeared in 1972, trumping Honda's CB750 with a 903cc motor, 82 HP and handling that was admirable for the time. By the end of the decade, bikes like the GPz550, GPz750 and GPz1100 were near the top of their respective classes, with torquey air-cooled engines, smart half-fairings and capable chassis packages.
But by 1983, Kawasaki had something very special up its sleeve. The GPz900R was set to launch and it would rewrite the rules for the superbike class. With a 16-valve, water-cooled engine, full fairing, advanced chassis technology and amazing performance, Kawasaki needed a name for this new era. Ninja was the sticker placed on the side of the bike, and it certainly fulfilled some of the criteria. It killed off virtually every other performance bike on the market and slaughtered the opposition at the 1984 Isle of Man TT races, where virtually stock bikes took the first three places in the Senior race. There was nothing lower-class about the GPz900R, but it did go about its work quietly, efficiently and effectively: just like the masked Ninjas of medieval Japan...
Since then, the Ninja name has found itself on the side of a whole heap of Kawasakis; from the little 250 twin, right up to the firm's ill-fated ZX-RR Ninja MotoGP bike. Here's a look at how the Ninja has evolved over the years.
GPz900R Ninja
This really is the bike that started it all, and it's hard to overestimate its importance. People talk about the Honda CBR900RR as the first modern superbike, but the GPz900R arguably broke even more new ground. It was water-cooled for a start, which wasn't a first in itself, but was a first for a large capacity four-stroke, four-cylinder motor. The engine design was extremely compact and its cylinder head and valve train were right at the bleeding edge of development. Four valves per cylinder and double overhead cams were, again, not new, but the chain drive for the double overhead camshafts was moved from the traditional central position to the end of the crankshaft, saving space and optimizing gas flow.
The result of all this tech was an astonishing 100 HP good enough for 150 mph.
That amazing engine was housed in a chassis that was less radical, but still extremely capable. The frame was a steel tube backbone design, with an aluminum box-section swingarm and the firm's Uni-Trak monoshock suspension system.
Brakes up front were a pair of single-piston floating calipers linked to a hydraulic anti-dive system that bit on fixed discs. Wheels were cast aluminum with a mighty 150-section rear tire, and the fully-faired bodywork was straight from the racetrack.
It's all stone-age stuff now, but class-leading for 1984. And in terms of influence, it showed how the inline-four, water-cooled, 16-valve, DOHC engine would become almost ubiquitous in Japanese performance bikes. The chassis was less influential, but the full fairing, twin front brake discs and monoshock rear all set a pattern that's been followed right up to today.