If the Z1300 was a martial arts fighter it wouldn’t be Bruce Lee — beautifully controlled power and aggression, lightning-fast kicks and flashing punches. No, the big Z would be Konishiki Yasokichi, the heaviest sumo grand champion of all time, nicknamed the Dump Truck. Splat! Boof! Ker-pow! You don’t mess with Big Zed. Not if you want to walk again.
Yamaha’s muscle bike was the torquey shaft drive XS1100, while Suzuki had the sports-orientated GS1000, and, of course, Honda grabbed the headlines with the 1047cc, 105bhp six-cylinder CBX. But at the Cologne Show in September 1978 came the Z1300. There may have been faster bikes, and there were certainly better-handing bikes, but when it came to bragging rights, Kawasaki Heavy Industries’ majestic flagship had it sewn up. With six cylinders, liquid cooling, shaft drive and a tire-smoking 120bhp at the end of the twistgrip, this was the most powerful production motorcycle in the world. Even if it did weigh a hernia-inducing 297 kilos, 655 pounds. Dry.
With only two valves per cylinder, the big DOHC Kawasaki didn’t exactly bristle with innovation, but there was plenty of state of the art engineering. Honda had taken only two years to get the CBX from drawing board to showroom, while Kawasaki spent five years developing the Z1300. That might go some way to explaining why the two giants of the industry built two very different engines. A large capacity across-the-frame six is going to be wide, but how wide depends on how you build it. Honda carved inches off the width by moving the alternator from the end of the crankshaft and mounting it above the gearbox and driving it off a jackshaft. As they wanted a sporty engine they designed an over-square engine for higher revs and settled on 64.5 x 53.4mm. Big bores mean there is room for 24 valves. Air cooling demands wide alloy fins to shed heat, and as Honda opted for six carburetors they angled the outer Keihins inwards so that the rider’s knees didn’t knock against them.
Fill the 27-liter tank with fuel, add oil and water, and the Z1300 is pushing 320kg. Konishiki Yasokichi, the heaviest sumo grand champion of all time, weighed 287kg (633lb) when he stepped into the ring…
Order the September/October 2024 issue of Motorcycle Classics to learn more about the Kawasaki Z1300. Contact Customer Service at (800) 880-7567 or contact us by email.
