The factory Yamaha team has revealed it reverted back to the 2016 YZRM1 chassis for the Valencia Grand Prix as its struggles with the 2017 frame continued.

Yamaha has struggled all season with its 2017 M1, with various chassis updates – including the introduction of a 2018 prototype at Silverstone – yielding mixed results for the factory duo of Maverick Vinales and Valentino Rossi.

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Vinales – who topped the twoday Valencia test in 2016 on the 2016 bike – had been struggling more so than Rossi at Ricardo Tormo, with the Spaniard unable to brake and turn how he wanted.

Qualifying 13th (but starting 12th due to a penalty for KTM’s Pol Espargaro), Yamaha opted to bring forward its plans to try the 2016 frame in the test, with Vinales immediately feeling better on the bike – though could only finish 12th after encountering an issue with his rear tyre.

“The feeling with the chassis was great,” said Vinales.

“Already in the first lap (in warmup) I did a 1m32s low, then on the second lap I was already one second faster – something I hadn’t been able to do all weekend.

“So already I was feeling great, and maybe I pushed too early and too much for the feeling, because I was feeling good.

“In the race, I think we had some issues with the rear tyre.

“The feeling I had with the rear was that the tyre was not working well, a lot of vibration at the end of the race. So I didn’t want to risk any more than was necessary.

“I’m happy, because the chassis was working really well this morning.”

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Teammate Rossi – who was fifth in the race – felt switching to the 2016 frame in Sunday warmup was the right choice despite a lack of setup time, but is still uncertain what the future holds for Yamaha as it seeks to cure its woes.

“For sure it was a risky choice, but with my (2017) bike we know moreorless less where we are and sometimes in a race you can understand more than in 10 days of testing,” the Italian explained.

“It is quite difficult to improve the bike a lot in just one day, and at the end I think it was moreorless the race that I could do with my (2017) bike from yesterday.

“We are in big, big trouble with the tyres, we don’t have grip and it is very difficult to ride.

“But I think we understand something interesting.

“This (2016) bike is easier to ride and you feel better in general. Sincerely, it is what I felt last year when I tried (the 2016 and) the new one.

“But it is also true that we are more in trouble with rear tyre degradation (with the 2016), so we have some other problem.

“I did the meeting with the Japanese and they are worried like me. But, sincerely, I don’t understand which one (chassis) will be the base for next year’s bike.”