Vinales, who won on his Yamaha debut in Qatar last year, was only 11th in both FP1 and FP2 as the 2018 MotoGP season kicked off.

In the combined classification, the Spaniard is right behind fellow Yamaha riders Valentino Rossi and Johann Zarco, who led the manufacturer's efforts in ninth and 10th respectively.

Vinales said the bike's problems have not changed since the Qatar pre-season test two weeks ago, but admitted he did not expect a major improvement.

"We have a bit of trouble in everything, in all areas, so we will have to improve part by part," he said. "With the electronics we also have a big problem.

"Tonight we are going to make a big change on the bike and we will try [again] tomorrow. The rear end does not have much grip and that creates problems for me at the front.

"I cannot explain why we have so many problems. The only thing I have left is to be calm, I know that I have the level and when we put the bike at the front I will be there."

Vinales added that he is riding smoother than last year in an attempt to adapt to the bike's weaknesses.

"I try to help, I try to be very gentle with the bike, trying to not make the bike [have] a lot of trouble," he explained. "I'm much smoother than last year.

"Last year I could be much more aggressive and push more the bike. I'm doing my best, we have to improve a lot the bike."

"Positive" day for Rossi

While Rossi echoed Vinales about the Yamaha having not changed much the same since the test, the Italian described his day as a "positive" one.

In FP1, he was second, 0.061s behind Andrea Dovizioso, and while he was only ninth in FP2, Rossi said it was down to an imperfect flying lap.

"The feeling during the day was quite positive because I felt good with the bike and also my pace is not so bad, also with the used tyre that is very important for the race," Rossi said.

"I didn't arrive in a perfect way and I lost something during my lap, I did some small mistakes and I pay, because my position is not fantastic.

When asked if he is also trying to ride smoother like Vinales, Rossi said he is sticking to his natural style.

"I ride natural, I think my riding is, I don't know, maybe half between smooth and hard," he said.

Additional reporting by Oriol Puigdemont