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

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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.

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