In the 1970s, Kawasaki was king of the large sport bike market with the 900 cc four-cylinder Z1, but Honda spoiled things in 1979 with their six-cylinder DOHC CBX Super Sport. Other competition from Japan stepped into the game as well as Yamaha built the XS 1100 and Suzuki the GS1000. A horsepower race was on.

Kawasaki’s responded to these challenges with the 1,285 cc six-cylinder, shaft-drive KZ 1300. At the time, its 120 bhp engine was the most powerful unit fitted to a production bike, and despite its substantial weight of 710 lbs (111 lbs more than the CBX) it could still do the quarter mile in11.96 seconds at 114.35 mph and reach a top speed of 142 mph.

Compared to the six-cylinder Benelli 750 Sei of 1975-88 (based on a Honda 550/4) and the 1979-82 1,084 cc Honda CBX, the KZ 1300 was huge but because it was water-cooled, it was about two inches narrower than the Honda, well proportioned and comfortable, with a smooth five-speed gearbox and triple disc brakes.

With only 2,000 roadsters made from 1979-80, it’s also relatively rare. Over the next seven years, it was burdened with touring fairing and luggage. Part of the blame for the KZ 1300’s weight was the frame, which was a beefed up version of the Z1, with 412 mm forks. Another was the engine itself, which weighed 286 lbs. That’s a pound more than an entire 250 cc Honda Nighthawk.

The KZ’s car-sized clutch led to shaft drive, which saved a lifetime’s supply of chains. Three twin-throat carburetors helped the bike achieve about 38 mpg and the large fuel tank had a capacity of six gallons. Fuel injection was fitted to the second series, which got an additional 10 bhp and smoother running. Parking the heavy KZ 1300 was not for the faint of heart, but at higher speed it handled well. Improvements included shorter bars to move the rider forward, and longer rear shocks to steepen the steering head.

As a long-distance tourer, the KZ 1300 was ideal and one owner received a 120 mph speeding ticket in Nevada while pulling a Coleman trailer. Usually finished in in darker colors, a KZ 1300 can be difficult to find, but it’s not a particularly expensive bike. The KZ 1300 was never sold in Japan due to a 750 cc domestic limit, though, so collectors there have been known to step up for a nice one.