ULTIMATE PS BIKES
What a lucky lot we are. Revel in this roster of the bikes that changed our lives
From the ’70s, to the ’80s, and yes, the ’90s too... the best bikes bar none of their time
The 1970s KAWASAKI Z1
By ignoring the conventions that previously dictated what big bikes were all about, Kawasaki set down a new set of rules and in so doing created the modern sportsbike. In a further twisting of the received norms, we have Honda to thank for Kawasaki making the first marker in the battle for superbike supremacy that propelled machine development in the 1970s.
When Honda launched the CB750 at thetokyo Show in October 1968, Kawasaki were already well down the line with a 750 sohc inline four of their own. Kawasaki immediately abandoned what would have surely have been seen as a copy of the Honda and went back to the drawing board to produce a bigger, better inline-four with two camshafts instead of a single knocker.
Ben Inamura was chief project engineer on the aborted 750 project and he got a second tilt at biking history when appointed head of Z1 design. In the autumn of 1972 he delivered the goods. although the Z1 project had been conceived as a balance between performance and usability, its 82bhp engine (around 15bhp more than Honda’s CB750 could claim) was the real headline grabber.
The 903cc Z1 didn’t fit any pre-existing capacity class and its square bore and stroke measurements (66 x 66mm) broke away from the accepted wisdom on how a big-bore bike should work. Likewise, the pressed-up roller bearing crank owed more to Kawasaki’s two-stroke heritage than to the CB750’S car-type plain bearing crank.and, to appease the growing eco-lobby, the Z1 pioneered the separation of oil mist from the crankcase breather, routing it into the airbox. Kawasaki claimed that this reduced hydrocarbon emissions by 40 per cent.
The design of the Z1’s engine was unconstrained by precedent but it informed a lot of the history to come.
“Kawasaki immediately abandoned what would surely have been seen as a copy of the Honda”