Kawasaki KR250GP 1977
Following the race of Gregg Hansford
Kawasaki’s Grand Prix efforts began in 1966 with a 125cc, water-cooled, 2-stroke, disc-valve engine – which won the 1969 title with Dave Simmonds on board. KR3 V-4 was also developed from 1967.
The company’s 250cc efforts began in 1967 with the much less exotic A-1R, based on their road bike. (Kawasaki A1-R 250 rotary valve racer) and later a smaller version of their 350cc Bighorn engine.
It wasn’t until 1975 that their first dedicated racing car design appeared, the KR250.
This is a pair of parallel disc valves with counter-rotating 180º cranks. The early bikes also used a conventional rear suspension layout but with only a single rear shock mounted on the RH side of the swingarm.
Severe engine vibration problems led to a redesign in 1977 with the engine changed to a 360º “Twingle” layout with both pistons rising and falling together. A single-shock rear suspension mounted in the center is also used from this point on.
The KR250 (and its brother KR350) were hugely successful from 1978 until they were discontinued in 1982.
Kork Ballington won both the ’78 and ’79 250 and 350 titles, with teammate Gregg Hansford finishing second at 250 and third at 350 in both years.
Anton Mang won the 250 title in ’80, ’81 and ’82 as well as the 350 title in ’81.
Light weight, good power, narrow profile and excellent ground clearance of the design are all major contributing factors to its dominance.
For 1978, power output was 62 hp at 12,000 rpm with a weight of 104 kg – for a top speed of about 250 km/h.
The bike seen here is the one that Hansford raced in 1977-78.
