Cycle News is a weekly magazine that covers all aspects of motorcycling including Supercross, Motocross and MotoGP as well as new motorcycles
Issue link: https://magazine.cyclenews.com/i/128087
By ALAN CATHCART PHOTOS By HENNY STERN he year 2000 saw the famous son of a famous father clinch his first-ever 500cc World Championship title, when the Racer Formerly Known as Kenny Roberts Jr., or KR Jr., became King Kenny in his own right just as his dad had done exactly two decades earlier in 1980, by winning the third of his 500cc world titles for Yamaha. Quite by chance, my opportunity to test the title-winning Roberts Suzuki RGv500 at Phillip Island the day after the fina I race of the 2000 season in Australia, came exactly one month to the day after riding the reversecylinder OW48R Yamaha in Holland the bike on which his father had clinched the last of his hat-trick of 500cc world crowns 20 years earlier. That came about on an improbably sun-blessed autumn weekend at Assen thanks to Arai Europe boss Ferry Brouwer, who commemorated T 24 JANUARY 17, 2001 • cue RAND the 75th anniversary of the historic Dutch circuit by organizing a series of demonstrations of the legendary bikes that helped create that history. One of those was the yellow and black Roberts Yamaha, which, thanks to the enthusiasm and commitment of British collector Chris Wilson and the inspired restoration work of former 500cc GP race mechanic Nigel Everett, represents yet another vital ingredient of the early days of 500cc two-stroke GP history saved from the scrap heap and returned to the racetrack as part of the Wilson collection. In fact, the Wilson collection of authentically restored 500cc GP racers has a pair of OW48R Yamahas in it, for alongside the 1980 Roberts machine is the 1981 Akai-sponsored version r'!ced by Barry Sheene at the start of that year under Erv Kanemoto's aegis, before the arrival halfway through the season of his OW 54 rotary-valve V-four. But the Roberts bike which Wilson found in Holland n • _ s •• (the site of Yamaha's European base) in dissembled guise has a very early chassis number, stamping it as a 1980 machine - and since King Kenny was the only Yamaha rider to use an alloy-framed OW48R that year, this puts his name on the bike, quite apart from the various trademark Roberts giveaways on it which he alone used. These include the Morris magalloy wheels (Sheene used Dymags, others Campagnolos); the upsized 320mm front brakes (others came with 280mm rotors) fitted with KR's special cooling ducts; a front caliper on the rear brake, complete with torque arm rather than a lug on top of the swingarm like on other 500 Yamahas (KR used the brakes very hard, especially the rear, compared to other riders); 40mm Kayaba factory forks with magnesium antidive and the recessed tops retained by circlips; and a tricked out De Carbon rear monoshock with separate gas canister, which only the factory bikes used. ON "It's basically a set of TZ500 cassette-gearbox crankcases with a special factory top end on them, with guillotine power-valves, a quite different stud pattern for the separate cylinders, and special porting," says Everett of the OW48R motor, whose only weak point seems to have been the extractable gearbox - a fact confirmed by former works Yamaha TTwinner Charlie Williams, who also rode the Roberts bike at Assen and recalled the time he was leading the 1981 Senior TT in the Isle of Man by a comfortable margin on an OW48R, when the gearbox broke flat out in top gear round the fast sweeper at Ballacrie, just after Ballaugh. Ouch! I can't think of a worse place on the TT Course to lock the back wheel. "Fortunately, it snapped a shaft, otherwise I wouldn't be here to tell the story," says Williams, "but just as I was coasting to a halt I remembered that when I went to pick the bike up in Amsterdam, I'd seen a skip full of junked gearboxes sitting outside the