The Gresini rider stunned with two victories in the opening four rounds, but lost the title lead with a fall at Portimao before an eighth-place finish in the Spanish Grand Prix.
“I’ve tried the new fairing. It’s not so bad, we have to check if I’ll try it also in Le Mans,” said Bagnaia, who set the tenth fastest lap time (+0.666s) during his 45 laps.
“The new one is slimmer. At the start it was strange for me – in the change of direction it’s really fast, but it’s a little bit more unstable. In this track, it was okay. In another track, I don’t know.
“But if the race was starting [at Jerez] now, I’d use the new fairing.”
As well as trying the updated fairing, Bastianini spent the first in-season test of the year experimenting with riding style tips gleaned from the data of factory Ducati race winner Francesco Bagnaia.
“I modified a bit my style because after the race I checked the data and compared with Pecco my style was too different and today I was riding more similar to Pecco. And at the end, I’m a little bit more faster,” he said.
“With medium tires we improved our pace by 2-3 tenths of a second, so overall this is good news. Then the wind came in the afternoon and I chose not to take any unnecessary risks.”
Rookie team-mate Fabio di Giannantonio, also using last year’s GP21, focused on set-up and ergonomics on his way to 19th place (+1.195s).
“We needed this test and we made the most of it,” said the Italian, still chasing his first MotoGP points. “ The work done during the weekend has naturally carried over to today; we concentrated on the feeling with the bike and I think it was a good day.”
The wind hampered di Giannantonio on his soft tire run but, “Even though the times don’t show it, I feel the bike a bit more mine. I was also able to try a new tank, a little bit more slender: as often happens, I liked some aspects and liked it less on others.”
Bastianini will head for round seven at Le Mans next weekend third in the world championship, 13 points from Aleix Espargaro (Aprilia) and 20 behind title leader Fabio Quartararo (Yamaha).