THE THREE-YEAR PLAN
It was only ever allowed to briefly exist for 36 months and yet no other Japanese two-stroke works 500cc Grand Prix racer got into the psyche of racing in quite the same way. The square-four rotary-valve KR500 Kawasaki defined the time within which it was
Rear: 150/70-18 Avon AM23 on 4.00 in. Dymag wheel.
Under the skin
Designer Kinuo ‘Cowboy’ Hiramatsu’s beautifully arc-welded light-alloy monocoque chassis followed the Ossa 250 design route in incorporating an integral 32-litre fuel tank mounted in the conventional position. Nevertheless, the Kawasaki’s fabricated frame delivered tremendous torsional and lateral stiffness with two outer side plates bolted to the rear flanks of the tank to support the footrests as well as the rear swingarm pivot. These were then cross-braced to an inner pair of plates attached to the back of the fuel reservoir. 35mm Kayaba forks mounted in Kawasaki’s own fabricated triple-clamps were fitted in a pivot mount welded to the front of the chassis, while the rear suspension employed a second-generation version of the Uni-trak rocker arm system seen on the KR250/350 tandem twins, but overheating of the rear shock was an ongoing problem, which meant that Ballington often suffered handling problems as a race wore on. Moreover, in addition to being overweight, with a 1470mm wheelbase the KR500 was also extremely long, even by the standards of the day – around 100mm rangier than its competitors, and while this meant it held a line well and was very stable under braking thanks to reduced weight transfer, it was also very slow steering in tighter turns. Like the Suzuki Gamma motor of similar architecture, the Kawasaki’s rotary-valve engine measured 54 x 54mm for a capacity of 494.6cc, and like the original RG500 was a true squarefour design with the cylinder tilted forwards in a single plane on the crankcases, not stepped as on the later Suzukis. All four cylinders were separate, with threetransfer/single-exhaust porting used at first in 1980, switching to a revised five-transfer layout in 1981, and the glass fibre disc valves fed by side-mounted 34mm Mikuni carbs. Perhaps because of this, there were four separate crankshafts geared together in pairs, with an underslung idler gear driving the dry clutch and water impeller on the right, and the ignition rotor on the left. The six-speed gearbox had no external access, so in order to change internal ratios the engine had to be dropped out of the frame and split open – still, at 90 minutes, this was not an overly time-consuming job, and with a choice by 1981 of four different ratios for the bottom two gears and top, and three for each of the others, this was an important asset.
How the KR was developed across the three years: Year one, 1980:
Kork Ballington’s main focus in 1980 was on developing the KR500 which suffered from the usual teething troubles of a new design, retiring from Misano and limping to 13th at Jarama. By the third GP, things were starting to improve and a first points-scoring finish at Paul Ricard appeared in Kork’s hands, finishing eighth. An abdominal operation then sidelined Kork for the next two 500cc races – but fifth place on his comeback in Finland was just the fillip the team needed, followed by seventh in the British GP at Silverstone. However, the KR500’S short debut season ended on a down note, with both Ballington and Hansford retiring – probably thankfully – from a damp race at the old 14.173-mile/22.80km long Nűrburgring circuit, both of them with handling problems caused by broken steering dampers. Though innovative in design and increasingly powerful, the 1980 Kawasaki KR500 suffered from a lack of acceleration out of slow corners, most likely due to its relatively porky claimed 138kg dry weight.
Year two, 1981
The KR500 in1981 had its weight pared down to a more reasonable 133kkg dry, thanks partly to magnesium crankcases, annd with a stiffer chassis thanks to a revised rear section and altered sideplates. Midrange power had been improved in an effort to resolve the acceleration problem, with five-transfer cylinders, new exhaust pipes and altered rotary valve inlet timing. The fairing design was changed to duct more cool air to the rear shock anda another innovative idea was added to what wasw already a forwardthinking motorcycle, in the form of a mechanical anti-dive system based onn that developed in the USA five years earlierr by Udo Geitl and Todd Schuster on their BMW RR90S Superbike. Aboard the revised bikee, Kork enjoyed his best season ever on the KR5000 in 1981, finishing runner-up to Crosby’s works Suzuki in the UK Shell series, and second to Haslam’s big fourstroke Honda in the Open class championship. At the South African’s season – in spite of complaining of the reviseed frame’s unpredictable handling at the limit – third place at Assen in a damp Dutch TT gave the KR500 its first-ever visit to a GP rostrum, a resultt not repeated a week later with a 19th place finish at a damp Spa, thanks to an ill-handling bike. But fifth at Imola presaged a thrilling race in the British GP at Silverstone, where Kork battled for the lead with Roberts, Mamola and eventual surprise winner Jack Middleburg, before retiring with a broken rotary valve ten laps from the finish, when still with a chance of victory. It was to be the Kawasaki’s closest-ever chance of a GP win, but Kork made up for the disappointment with another front-row start in Finland – and another third-place rostrum finish, ahead of all the Yamahas, before placing fourth in the Swedish GP the following week at a wet Anderstoorp, after initially leading the final GP of 1981. Ballington had finished eighth in the World Championship in what was to prove too be the Kawasaki’s best seasonn.
Year three, 1 982:
For 1982, the Japanese e factory engineers tried to reduc ce weight still further with a semi-monocoque spine-frame design wh ich had a separate alloy fuel tank k mounted on top and now used Showas suspension, though sti ll with the mechanical anti-dive. Th his failed to live up to the promise of th he 1981 bike, with Ballington – again the singleton Kawasaki rider – never finishing higher than sixth in a race, en route to ninth place in the 1982 Worl d Championship. However, he did take thet British Shell 500cc title very easily, albeit m mainly against privateer opposition, winning th he last six races of the eight-round series. Bu ut by the time Kork clinched the crown by winning the final round at Oulton Park in October, Kawa asaki had already announced its retirement from Gr rand Prix racing – “in order to concentrate our comp pany’s race activities on those classes of four-stroke racing directly related to our customer products,” s said the official press release.
The history books have archived the green bike as a leading support act to the Yamaha/ Suzuki battttle for world honours for three short seasons from 1980 to 1982. In reality, the bike that Kork rode is much, much more important than an ‘ also’ honours tag. Though it never won a GP race, and only twice finished on the rostrum, the bright green monocoque-chassised Kawasaki was a constant presence for these three years on race grids in Europe and, in 1982, in the USA as well, where it gave future world champion Eddie Lawson his first taste of riding a 500GP bike, allowing him that year to lead the Daytona 200 for the first time, before retiring with transmission problems. The KR500 was a bike which seemed perpetually on the brink of becoming a major force in 500GP racing, just as its KR250/350 tandem-twin kid sisters had blitzed GP racing’s middleweight classes in successive years for more than half a decade. But, it never quite happened, and when Kawasaki called an end to the project at the end of 1982 and withdrew from GPS to concentrate on four-stroke racing, the KR500 moved from being a ‘ what-if’ threat to the established order, to a motorcycle that ‘coulda-bin’ a contender. Fortunately, a handful of the mere dozen or so KR500S which Kawasaki built over the bike’s four years of competition have survived in private hands, and one of these – arguably the most successful of all, which the official factory team records list as the one which Ballington took to third-place GP finishes at Assen and Imatra in 1981, followed by fourth at Anderstorp in the final GP of the year – was acquired early in 1998 by British enthusiast Chris Wilson, from a private collection where it sat unused for more than a decade. Two weeks later, Kork himself paraded the bike in public for the first time in 15 years at the Assen Centennial TT event – but sadly it seized after just half a lap, thanks to faulty ignition timing. Fortunately, also included in the sale was a large quantity of parts and most of a spare engine – so, as with all Team Wilson’s prized collection of factory GP racers, the KR500 was completely rebuilt by former works Kawasaki mechanic Nigel Everett’s Racing Restorations company to the superb race- ready condition which it is in today.
The KR500 is an engineer’s bike, one where function and form go hand in hand, replete with a host of idiosyncratic features which set it apart from all its contemporaries. Like the artistic designg of the monocoqueq chassis, so beautifully arc-welded in its construction, yet so obviously crafted by hand, not by a welding robot. Or the large circlip holding on the rear sprocket, making it quickly detachable for fast gearing changes. Or the screw-off ends to the gold anodised silencers, for easy repacking at the whim of the noise police. Or the complex fabrications that comprise the triple clamps, each welded up by hand from aircraft alloy. Or Kawasaki’s own distinctive brakes, with the aluminium calipersp hand crafted from solid billets. Or the distinctive mechanical anti-dive linkage, so plausibly effective Honda ended up copying it on their RS1000 four-strokes. Or the large diameter front axle, for greater rigidity. Or – well, examine these photos and see for yourself, for this is a masterpiece of Oriental motorcycle art. The KR5500 belongs to the pre-kobas era of GP design, before the Spanish engineer who created the modern two-stroke racing motorcycle e’s chassis geometry started lifting the reara ridde height, steepening head angles and reducing wheelbases. This means that, in spite of the rocker-arm monoshock rear end, the lengthy KR500 is both rangy and relatively low-slung: it sits low at the rear, perhaps to enhance stability under braking via reduced weight transfer – a reason too, perhaps, for the stretched-out 1470mm wheelbase.
Seat to footrest height is also very reduced, making it quite hard to hang off the bike round turns, which you feel needs doing in order to make it turn better because of that rangy build that invites you to keep up turn speed. That’s instead of using the extremely effective Kawasaki front discs, which have a lot of bite and feel by the standards of the era, to brake deep into the apex and then turn the bike. Kork Ballington’s flowing 250/350cc riding style would have been well suited to the KR500.