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GP Week : Issue 13
M oto GP news >> Honda pans 250 replacement formula HONDA, widely believed to be the power behind the assassination of the 250 two- stroke class, has spoken out against Dorna’s proposal for strictly-controlled 625-650cc four-cylinder four-strokes, saying that it would be difficult to supply low-cost racing engines in this quirky size. The capacity was chosen to avoid a direct clash with the World Supersport championship, run alongside the Flammini Group’s World Superbikes, and fielding production-based 600cc machines. HRC managing director Kosuki Yasutaki said at Mugello: “It’s difficult for us to make a 625cc engine – we would prefer 600cc. We think that regulations should be so we are able to supply machines for the new class,” he continued. “Dorna’s proposal is uncertain … maybe there is some condition or restriction to the proposal. We hope that Dorna, the FIM and the Flammini Group have a good discussion to resolve this question.” Yasutaki said there was “no way back” for 250 two-strokes, in spite of a groundswell of opposition within the paddock. All the manufacturers supported the move to four- strokes, he said. “But all want to go in different directions.” Suggestions have ranged from 400cc twins (half MotoGP engines) to singles of a similar size; as well as a ‘control’ four-cylinder motor – though it is far from certain who would supply it. The GP Commission meets this weekend at Catalunya, and delegates are expected to respond to Dorna’s proposal. Agreement seems a million miles away, and the fear is that Dorna might step in with a diktat in line with the 625-650 proposal. THE wait is over for Honda’s pneumatic-valve engine. The machine appeared, and raced, at Mugello, in the hands of former GP winner and now factory test rider, 41-year-old Tadayuki Okada. And though he did no better than 14th, he at least considered the exercise successful. “We found out a lot more than in testing, but there was not enough set-up time for the machine to make a difference. If it had been dry, I think I could have showed a better performance,” he said. A decision on whether the regular Repsol Honda team riders Pedrosa and Hayden will race the bike at this weekend’s Catalunya GP will be made after examining data and consulting the riders. At the least, the bike will be available for them to test the day after the Catalunyan GP – more units are already being flown from Japan in readiness. Apart from desmodromic Ducati, Honda will be the last to switch from steel valve springs to pneumatic valve actuation. Honda are targeting acceleration and top speed, and the latter at least has been achieved, with some 1,000 rpm added to the top of the rev range; although Okada revealed that there was still some difficulty with mid-range response. The motor is completely different from the interim valve-spring model currently used, but fits straight into the chassis. Okada has been testing at Motegi and Suzuka in Japan, but project leader Shinichi Kokubu said: “We wanted to get development data at a Grand Prix circuit, to study and verify the performance,” he said. Okada qualified within 1.7 seconds of pole, and spent the race dicing with Kawasaki’s Anthony West, finishing 14th. “With better traction, I could have done much better. The data showed my speed was 327 kmh, but if I had come off the corner I believe it would have had five kmh more … overtaken the Ducati for sure,” he smiled. The reduced engine friction made the bike feel quite different, he said, in the same way that the old 500 two-stroke Big Bang and Screamer were identical in weight distribution, but gave the rider a completely different feeling. In particular, it improved the feel on corner entry – one area that Hayden has consistently complained about with the valve spring engine. Mid-range performance was still an issue at a stop-and-go circuit like Motegi, Okada said, but no problem at a flowing track like Mugello. “The power delivery is not in a straight line,” he explained. 13