The Aragon MotoGP weekend has exposed fresh tension between Yamaha and its Honda-bound star Fabio Quartararo.

It came amid an uncharacteristically subpar outing for the 2021 MotoGP champion, who struggled to competitively assert himself against the other Yamaha riders - and finished the grand prix last, nearly 52 seconds back from the winner, after going off multiple times.

Quartararo and Yamaha seemed to have settled into a 'truce' of sorts after the Frenchman resolved his future. Disappointed with Yamaha's development efforts for nearly half a decade, Quartararo never entertained penning a 2027 deal with his current employer - admitting recently that he never initiated any renewal talks before committing to Honda instead in the off-season.

But this ultimately seemed to settle things. With Yamaha firmly in a 'rebuilding' year as it focused on exploring its first attempt at a V4 engine, Quartararo has produced the occasional heroics and fairly reliably led the line within its four-rider regular roster.

He has also publicly accepted that Yamaha would deprioritise improving the current 1000cc bike ahead of the 2027 switch to 850cc and Pirelli tyres, acknowledging that this made sense for the project.

Yet doing development work that could benefit that 850cc project appears to be where Quartararo draws the line.

He was uncomfortable with the bike during the Aragon weekend but also unsettled by Yamaha's requests to re-test a new chassis that he had already found lacking.

"It's worse," he insisted on Saturday. "Yesterday I said it was worse, they wanted me to compare again this morning, it was worse [again]. I was more of a test rider this weekend, testing three times the chassis, it was not working. We had a new linkage also, it was not improved."

He took a firmer line on Sunday, saying that he will "stop trying 100 things in a weekend".

More revealing, though, were his reported comments to French media in attendance - in which he said he would not be aiding Yamaha's development due to "personal reasons".

This comes off as particularly unseemly given Quartararo has been very well-compensated in this contract cycle for limited on-track results (though they have clearly been limited by machinery rather than his own underperformance), and perhaps Quartararo himself is aware of this - because, according to French reporters, he subsequently revealed that these "personal reasons" were what he claims is a Yamaha refusal to allow him to try the Pirelli tyres in the Red Bull Ring test after the Austrian Grand Prix.

Yamaha will never put him on the 850cc bike, which it is developing with testers Augusto Fernandez and Andrea Dovizioso - but one idea that has been floating is at least giving riders in contractual situations like Quartararo's a shot at running Pirellis on the current 1000cc machines.

Whatever the precise details of that test, there's now again an added needle over the final eight rounds of the Quartararo-Yamaha partnership - which was once one of the best stories in MotoGP.