Despite leading both days of the Valencia post-race MotoGP test, Maverick Vinales is reserving judgement on which of the two new Yamaha engines he prefers until trying them again at Jerez next week.
Vinales had set the pace with a 1m 31.416s on day one, remaining on top after lowering his best to a 1m 30.757s despite a fall on day two.
But the top priority this week for Vinales and team-mate Valentino Rossi was to try two new engine specifications.
"Nothing else. Just the engines. The most important thing!" smiled Vinales, riding with his new #12.
Yamaha is seeking a smoother engine to cure its acceleration and rear tyre life issues.
On Tuesday the initial 2019 version offered a clear improvement over the 2018 design, but then when the second 2019 spec was rolled out on Wednesday it was hard to pick a favourite between them.
"It's very difficult," said Vinales. "I could not be let's say 100% sure which engine is better, so I think it's better to try in Jerez and try to be more precise. Here was difficult because the track changed quite a lot.
"I think there are very small differences, but it makes a lot over one lap. So we need to be sure which engine we prefer.
"Most of the time I rode with the same one, where I felt better on engine brake, because I want to concentrate a lot on entry to the corner. Because I think when we lose grip that is where we lose [time]. So it is important and today I felt strong going into the corners.
"But anyway still there is a lot to do on the top power to make it smoother, because still it's aggressive and I lose a lot of traction. So in Jerez it will be very important to choose the engine.
"As I said, we're going to try them more, we're going to be more convinced about the engine decision, but the direction we are following is the correct one."
Vinales had mixed feelings about setting the fastest time at the test, having delivered a quicker 1m 30.189s to lead the same test a year ago, but pointed out he had done no real dry set-up work after the wet grand prix weekend.
"Not so bad. It depends how you compare because last year we were faster, but I think the track conditions today were not great and it was very slippery. Especially the front," Vinales said.
"So the bike is working when the track is slippery, which is a really good point. Also we didn’t try anything on the set-up and I felt there we can make a big step. So I'm happy that only with the engine we improved some tenths.
"We'll keep working. I think to get a smoother bike will be very important, especially when there is no grip in a race. But there are some upgrades that still need to arrive that help…"
Vinales finished the test 0.133s clear of Ducati's Andrea Dovizioso with Honda's world champion Marc Marquez completing a top three covered by 0.154s.
Rossi was ninth fastest (+0.614s).
