Valentino Rossi has confirmed that Yamaha’s 2018 MotoGP bike will be based on its 2016-specification M1 after a private test in Sepang.

Both Rossi and Maverick Viñales of the factory Movistar Yamaha team and Tech 3’s Johann Zarco participated in the test, during which they compared the 2016- and 2017-spec M1s.

They had done the same in the official post-season test in Valencia, days after Rossi and Viñales reverted to the 2016 bike for the grand prix at the Circuit Ricardo Tormo.

Rossi has revealed that all three agreed at Sepang that Yamaha should ditch the troubled 2017 bike and stick with the 2016 version that Zarco used to such good effect during his rookie season.

“We tried the old bike, the one from 2016,” Rossi told Italy’s Radio Deejay. “We deliberated and we were all agreed the 2017 bike was worse.

“We still have to see what the new bike will be like, there will be something interesting. But the base will be the bike from 2016.

“Now is a critical moment. Between now and February, Yamaha needs to make a big leap forward.”

Reflecting on a season that yielded fifth in the points, Rossi said his mistake was to assume that the problem was with him and not the bike when Viñales went fastest in last year’s Valencia test.

“The problem was that when Viñales arrived, he went very fast,” Rossi added.

“I tried it and I didn’t like it, but I thought, maybe because it was the end of the season, I was out of shape.

“So we continued with that project (the 2017 bike), but this was a mistake because we lost a lot of time.”

Pre-season testing begins in Sepang on January 28-30, after the winter testing ban.