Kawasaki KR250 Race Bike

Kawasaki KR250 Race Bike

Kawasaki KR250The Kawasaki twin had one of the longest gestation periods of any post war race machine. An early prototype of the KR was first seen at the 1970 Amsterdam motorcycle show, it didn’t turn a wheel in anger until March 1975 when Canadian Yvon Duhamel rode one at Daytona. Soon after the KR was entered into the fray at GP level and showed great potential. The first variants featured a seven-speed gearbox and one version of that had two different top gear ratios used on the US banked tracks, one ratio for the downwind fast section and a higher gear for the slower, into wind, run on the opposite side of the bowl.

KR250When the KR was brought to Europe the seven gears had to be limited to just six, but even so the inline twin was competitive from the outset. The great advantage the Kawasaki offered was the overall weight, the early versions tipped the scales some 5kg less than a TZ250 Yamaha but produced more power. The KR250 suffered from lack of development during the first few seasons, often showing great potential only to suffer a mechanical failure and be forced to retire. The engine originally used a 180-degree firing order but this caused excessive vibration so the twin was redesigned enabling the pistons to rise a fall in unison, in 1977 the twin shock rear suspension also came in for revision becoming the now familiar Kawasaki Uni-Trak design.

Development stepped up a gear for the 78 season and a complete redesign of the engine was carried out in a bid to increase reliability. A larger capacity 350cc model was also introduced that year and together with South African Kork Ballington the KR models became invincible taking both the 250 and 350cc world titles during 78 and 79. Anton Mang continued the success by taking the 250 title in 1980 and 82, and repeating Ballington’s double success in 1981. The overwhelming success of the KR250 wasn’t an awful lot to do with the Kawasaki Factory as little development was carried out on the machine once the design became established, however, Ballington enjoyed the considerable services of his ace tuner brother Dozy, while Mang was similarly graced with Sepp Schlogl as his chief mechanic. The two separate teams going on the make their respective machines into very quick and competitive race ware, often using very different ideas with the end result often being the Ballington machinery differed greatly from the Mang KR’s.

Kawasaki KR250The disc valve twin has a bore and stroke of 54mm x 54.3mm giving it a capacity of 247cc, fed by two magnesium Mikuni carburettors that protrude from the left hand side of the engine, it pumps out around 62bhp at the rear wheel. The Kayaba rear suspension unit is coil sprung with oil and nitrogen damping, but surprisingly is not adjustable. Above the shock absorber is the rocker arm that connects it to the swing arm and the chain adjustment is by eccentric cam, this feature later became standard on most Kawasaki road machines. Keeping the front wheel bolted in place, the business like forks are standard 34mm Kawasaki oil damped items, with internal adjustment for compression damping and a second set of lugs for running a twin disc set up. In fact only Greg Handsford actually used this facility and considering Mang’s obsession with weight and performance I am surprised he never machined the extra lugs off. The silver box visible immediately above the front mudguard is the CDI box that feeds the HT coils tucked away under the front of the tank.

Kawasaki KR250 engineThe right hand side of the engine is the busy part with the ignition, clutch, water pump and tachometer drive all running off the ends of the two counter rotating crank shafts with all this activity it still manages to avoid looking in any way untidy. Any routine maintenance is relatively easy compared to some of the factory bikes of the time. The dry clutch is made up of sixteen plates in total, comprising of seven friction and nine metal plates and from there, the power travels to the rear wheel via a six-speed gearbox with up to four possible ratios for each gear.

The sleek lines of Mang’s bike were not at all like the other KR250’s of the factory teams as Mike Krauser had developed this particular fairing in extensive wind tunnel tests during Mang’s privateer season of 1980. It obviously worked as Mang continued to use the design throughout his time with the Kawasaki team until his defection to Suzuki in 1983. Ground clearance is nothing short of awesome with everything tucked well out of the way and only the one exhaust pipe running between the lower frame rails, the other exits out of the left hand side of the seat unit. Sitting on the bike only serves to emphasise its minuscule proportions and is certainly a lot lighter than its contemporaries such like the TZ250 Yamaha’s, in fact it feels more like a 125 to sit on especially when you adopt a racing crouch and attempt to get behind the bubble.

The final versions of the KR featured a unique belt drive later seen on road going Kawasaki middleweights.

Kawasaki KR250 Specifications

  • Engine: Liquid-cooled in-line two-stroke twin
  • Capacity: 247cc
  • Bore & stroke: 54 x 54.4mm
  • Carburetion: 34mm Mikuni
  • Max Power: 56bhp @ 12000rpm
  • Torque: 35ft-lb @ 10000rpm
  • Transmission: 6-speed, dry clutch, chain final drive
  • Frame: Steel tube double cradle
  • Suspension: 36mm telescopic forks Uni-Trak rear
  • Wheels: 3.25 x 18     3.50 x 17
  • Brakes: 310mm disc twin opposed piston caliper, 210mm disc twin opposed piston caliper
  • Weight: 104kgs
  • Wheelbase: 1360mm
  • Top speed: 155mph

Kawasaki KR250 Gallery

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