VJMC’s Steve Cooper remembers…
With the YZR finally in fine fettle, Yamaha looked to be in with a shot of reclaiming the title
Rider coach, trackside fettler and GP guru Kel Carruthers had gone but Yamaha was still in dire need of reclaiming the prestigious Number One plate. As was always the case, ‘more power’ was thought to be the answer and the boffins back at Iwata somehow managed to work in an additional pair of transfer ports into the YZR’s cylinders. The result was an extra 10 or so horses, bringing the V4 reed valve motor up to some 165bhp on the dyno even if the factory only ‘officially’ quoted 155.
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Some 500 riders had perfected the art of ‘squaring off’ corners aided by Dunlop tyres that facilitated controllable rear wheel slides. Yamaha factory teams were on Michelins which had stronger side walls aiding back wheel grip and generally delivered better lap time but with a caveat – when the French tyres had reached their limits they let go almost instantaneously.
Eddie Lawson was back with Marlboro Team Roberts having found Honda’s NSR500 just too unpredictable. However, his season proved to be dire with only 118 points after braking both ankles in different races. Wayne Rainey was going to have to shine – which he did. Gauloises Blondes Yamaha/Mobil 1 would field two homespun riders in the guises of Christian Sarron and Jean-Philippe Ruggia. Three other riders were on the YZR500 with varying levels of semi-official factory support.
The bike was a winner pretty much out of the crate with the new motor but that didn’t stop the R&D guys looking for small improvements that might gain the extra crucial points here and there. Moving the engine upwards and forwards aided front-end feel and fitting the swing arm with eccentric bearings delivered the ability to subtly change ride height from circuit to circuit. The YZRs were heavier than the RGs and NSR so the factory even went to the lengths of producing titanium exhausts for the final few races.
At last Yamaha had the bike sorted and other than retiring at the penultimate Hungarian GP, Rainey completed every race. With seven wins, five second places and two thirds it was a done deal with 255 points against second place rider Kevin Schwantz on the Suzuki. Unfortunately, none of the other riders did well – but Yamaha had won its all-important sixth Manufacturer’s Championship.
The OW01 motor had proved its worth and Yamaha would go into 1991 selling satellite teams such as Harris and ROC Yamaha versions of the 1990 engine to stimulate the GP500 class and effectively share the joy. The firm had high hopes for the following year!
