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Yamaha YZR500 vs Suzuki RG500 seen from the 21st century (part three)
Yamaha YZR500 vs Suzuki RG500 seen from the 21st century (part three)

Yesterday we were talking about the Suzuki RG500 with which Barry Sheene dominated the 1976 and 1977 world championships. Today we are going to talk about the Yamaha YZR500. This bike was the first to win a world championship with two-stroke mechanics in the hands of Giacomo Agostini, but until it established itself as the champion bike it was, it had to spend a couple of years in the wake of the Suzuki driven by Sheene.

And it is that a somewhat particular North American had to arrive to show that the motorcycle not only it was a winning motorcycleIf not, Yamaha had the ability to design technical solutions that improved the performance of its racing bikes. But let's not anticipate events and see how this development and subsequent success were.

Kenny Roberts Champion in the 78, 79 and 80

I imagine that while the grills were dominated by Suzuki and Barry Sheene, at Yamaha they would not be very comfortable. Although with all this dominance, for the 1978 500 cc season they continued with their strategy of not signing a leading rider or supporting him with a factory team. Luckily, in the USA Kel Karruthers noticed a young driver who had won everything in the AMA championship and, after obtaining financial support from Goodyear, they landed in the world championship with Kenny Roberts and the Yamaha YZR500.

Roberts was the ideal rider for this new type of motorcycle and his way of conducting them. He was one of the first to understand that the most dangerous point in a race was when braking and drawing the curve, so he tried to minimize that moment as much as possible to take advantage of the virtues of the bike he had. The greatest virtue was the acceleration, so the sooner the bike was upright, the sooner it could hit the gas and the sooner it would reach the next corner. What happened around the corner and when braking did not interest the American driver much.

There are those who say that Roberts evolved his technique by seeing Jarno Saarinen driving, but as Saarinen died very young in the Monza accident of 1973, he could not evolve his peculiar way of driving with his knee touching the asphalt. Which is what the American did, who also had the experience of the Dirt Track, in which the bikes skid for a long time to the limit of the grip of the tires on the ground.

In the mechanical part, the engine of the Yamaha YZR500 was an inline four cylinder with a single crankshaft rotating in the opposite direction to the wheels. A bad beast that had a useful power band of just 1,500 rpm and also consumed gasoline as if it were free. So the Yamaha engineers got down to business and came up with a couple of solutions to improve the response of the car. On the one hand, the intake was made through the piston skirt, which had a window that coincided with the intake manifold. In this way the crankcase was filled with fuel without anything to obstruct its passage or leaks through the gaskets of the disc valves. But the real revolution came on the exhaust side, since a valve was installed that partialized the gas outlet, thereby improving the engine's response at low revs and also helping to reduce fuel consumption since not so many gases escaped. unburned cylinder.

Kenny Roberts achieved three consecutive world championships with the Yamaha YZR500. Winning four races the year of his arrival in the championship, just when it was thought that he would familiarize himself with the European circuits. With which he earned the nickname of "the Martian" for his curious style of piloting and for his character, difficult to understand for the Europeans themselves.

Technical sheet Yamaha YZR500 OW48R

Tomorrow, to close this mini series, we will bring you a video of the best race contested by these two drivers face to face with their two-stroke machines.

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