Yamaha has been working on a new M1 in order to work its way back up the grid, having successfully convinced star rider Fabio Quartararo to stay with the marque for another two seasons.
The overhaul of the M1 covers everything from chassis, swingarm, electronics and aerodynamics, with the new bike making its first public appearance at the post-Spanish GP test at Jerez last Monday.
But while Quartararo could feel a “massive change” on the all-new M1 as he got to grips with the bike, team-mate Rins struck a downbeat tone after encountering some problems, particularly with the engine and the fairing.
"Monday was a very productive day in terms of new parts," he explained.
"We had a lot of things to test, big things and, of which, let's say, half and half worked. The aerodynamics worked quite well. I'm happy with the testing we did in that area, with a lot of comparisons, we focused on doing concise tests.
"On the other hand, the chassis didn't go as well as we had hoped, there's a lot more we can get out of it. We tried to make some chassis configurations to get the most out of it, but we couldn't get the most out of it.”
Following March’s Portuguese Grand Prix, Yamaha revealed that it brought a new engine for Quartararo to run in a private Portimao test. But the session was almost entirely washed out, with the French rider only managing to complete six laps on the upgraded M1.
The same new motor, which also completed plenty of miles with test rider Cal Crutchlow at Barcelona and Mugello, made it to Rins’ race bike at Jerez during the grand prix - with Yamaha allowed free engine development under the concession rules.
But the Spanish rider said he was struggling to tell the two specifications apart, as it didn’t bring any performance advantage for him.
“We fitted it over the weekend, but it doesn't change anything. It doesn't have more power, no,” he said.
“If you ask me, I've been all weekend with two different bikes and two different engines, the old one and the new one, and I haven't noticed any difference.”
Among other changes to the M1 was a three-part Formula 1-style fairing mounted to the front, but the impact of the new part was limited according to Rins.
“I expected to have more effect with this fairing, seen from the outside,” he admitted. “Maybe it was a failure on my part to see it because I had higher expectations about its effect on the bike's behaviour.
“But on the track, although there has been a bit of a change, it hasn't been much.
"In the end finding a big difference with a fairing is complicated and they haven't really had much time to work on it either.
“What they have done, they have done it well, I like it, so we will test it again at the Mugello test, after Le Mans, and if everything goes as we hope, maybe at Barcelona we can take it.”
