Reigning MotoGP champion Marc Marquez says he is not yet able to keep consistent pace with the new winged fairing introduced by Honda in Sepang testing.
Alongside his factory team-mate Dani Pedrosa and test rider Cal Crutchlow, Marquez trialled the new fairing on the second day of pre-season MotoGP running on Monday.
The riders confirmed the new fairing helped with wheelie reduction and braking stability, but Marquez admits he is worried about using the specification over a longer run.
"Of course the main target of the new fairing is the wheelie, try to stop the wheelie, try to have more downforce, then you lose a little bit of top speed," said Marquez.
"Of course braking stability, if you have the wings, becomes better, but then when you start to go in it looks harder. The bike on the fast corners also looks a little bit more hard.
"I think with that new fairing we need to find a good bike balance, because for one lap I can ride well and fast, but to be consistent I'm scared a little bit to overheat the front tyre, or something like this."
Pedrosa said he did "a lot of testing" with the new fairing, adding: "Of course, [it has] some positives, like the wheelie is better - but then in the corners a little bit different feeling. We still need to see if it's good for every track.
"We had only this spec. After the first feelings, now we have some information, so they [Honda] can work more on that fairing, to see if they can keep, modify, or see what's requested [by the riders]."
In addition to the fairing, the Honda riders continued to trial different engine specifications, as the manufacturer now looks set to choose between a version used in the post-season test at Valencia and a newer specification.
"Basically we concentrate a lot on the new one, the last test one," Marquez explained. "But of course we work also on the step of Valencia.
"At this circuit sometimes you can make a big mistake, because always here if you have more power, more torque, you are faster and you feel better.
"It's really important tomorrow to decide which engine is the best one. Looks like all Honda riders go to the new one but honestly still I have some doubt, because the new one still has some points that maybe in another circuit we can struggle.
"It's a very special circuit here, just two/three circuits during the season are like this. The other circuits are completely different so it's important to understand."