Valentino Rossi doesn't believe changing the MotoGP engine-freeze regulations would solve Yamaha's current acceleration woes.

Unless a Yamaha rider wins at Aragon this weekend, the factory's losing streak will reach 23 races, its longest barren run in MotoGP.

"On paper, this track is quite difficult and we arrive in a difficult moment from the technical point of view. So it will be not easy, but we will try the maximum," Rossi said at Aragon on Thursday.

"Usually it's tracks where the grip is not fantastic where with the Yamaha we suffer a bit. Also there is a big stress on the rear tyres here because you have a lot of long corners and under this point of view we suffer also."

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While Rossi has long highlighted electronics as the M1's biggest weakness relative to Honda and Ducati, which he believes "understand something we don't" with the single ECU, he later conceded that the solution will be "a combination between engine and electronics".

That prompted speculation over what kind of Yamaha engine modifications could be needed, from a change in crankshaft mass to a switch from an Inline to V4 cylinder layout.

But none of those things can be done during the season due to the development freeze, which forces all non-concession manufacturers - Honda, Ducati and Yamaha - to use the same engine design from the first to last race.

Given that other manufacturers have come to regret their start-of-year engine choice, most notably Suzuki in 2017, there have been suggestions that the freeze should be loosened to allow, for example, engine design to be changed once per season.

"I read this somewhere, about the engine. For me, the engine is a part of our problem but unfortunately it's not only the engine," Rossi said.

"It's true that with this [engine freeze] regulation you cannot modify during the season. But for me, a lot of things are also from the electronics and with the electronics you can work during the season.

"So it's not a problem of the rules.

"For me, we have to improve the engine and it's a part of our problem, but not the total."

Backing up Rossi's theory is that he previously stated Yamaha has been suffering relative to Honda and Ducati "since August 2017."

In other words, the acceleration problems - "we spin too much and are not able to put enough power on the ground. At the same time, we use the rear tyre too much" - were spotted after the halfway stage of last season.

Given that timing, and the development freeze, whatever Ducati and Honda found is unlikely to be purely engine related or it would have been apparent from the very start of 2017.

That's not to say Yamaha doesn’t need to modify its engine as part of the solution to its low grip/acceleration issues, but does underline that - as Rossi believes - the biggest step could well come from electronics.

Given that electronic developments - which in the unified software era usually means changing 'calibration' numbers used by the ECU when performing its calculations - are unlimited, the breakthrough Rossi is waiting for could potentially emerge at any moment.

"The good thing with the electronics is that it is not like fixing an engine, chassis or swingarm. You can fix it with a number, so you can fix it in a short time," Rossi had said at February's Thailand test, when he also warned: "But I'm quite worried because if we don't fix it now, I'm not optimistic to fix it by the first races..."

While the nine-time world champion is still waiting for an effective solution, team-mate Maverick Vinales felt some progress was made with the electronics during recent private tests in Misano and Aragon.

"Yamaha modified something [with the electronics] that is a little bit better, but unfortunately for me it is not a big step," Rossi said on Thursday evening. "But I hope that I'm wrong and Maverick is right!"