Yamaha riders Valentino Rossi and Maverick Vinales had new parts for both this season and next during day one of the Misano MotoGP test.

With just two race wins since Assen 2017, Yamaha has often been criticised for not offering enough significant new parts for the race team to try.

However, there was plenty on the agenda for Rossi and Vinales on Thursday, including the debut of a carbon fibre swingarm and new exhaust for the current M1, plus an updated engine for the 2020 prototype first seen at Brno earlier this month.

But neither rider felt any of the developments offered a major breakthrough, despite finishing fourth (Vinales) and fifth (Rossi) on the timesheets, within just 0.3s of Petronas Yamaha pace setter Fabio Quartararo.

"We need to keep working, it's not the step I think we could make," a downbeat Vinales said of the new parts.

"It's been a difficult day. I struggled to find grip. I didn't feel comfortable on the bike. Tomorrow we need to find another set-up or other things to improve the bike."

Rossi was more positive and, if all goes well with the carbon fibre swingarm on Friday, looks likely to try the part during his forthcoming home grand prix at the same track in mid-September.

"We had some interesting things to try and it was a good day of tests, because I was quite strong all day," said the Italian. "We started with the 2020 bike and afterwards we worked on this year's bike, which also had some different things. All the stuff was quite good and our pace was not so bad."

Definitely Maybe: Carbon fibre swingarms in MotoGP

Ducati has used a carbon fibre swingarm since the end of 2009. Honda then became the first of the Japanese manufacturers to switch away from aluminium last season, when Aprilia also began developing a composite swingarm.

With KTM successfully debuted the part from Le Mans this year, only Yamaha and Suzuki were without the option of a carbon fibre swingarm.

That was especially surprising for Yamaha given the M1's tyre and traction issues, which carbon fibre is widely credited as aiding, but Rossi had confirmed it was in the pipeline last Sunday at Silverstone:

"I asked for it a lot of times. I think the carbon swingarm can help us, so I hope Yamaha bring it as soon as possible. I think that in not a long time we can see it…"

Indeed, the carbon fibre debut turned out to be just days away.

As well as being lighter than aluminium, carbon fibre can be better tailored to provide different stiffness properties in each direction, by changing the number of layers and orientation of the fibres.

That opens up a huge, but potentially overwhelming, range of new design possibilities compared to aluminium. However, a difference in natural damping between the two materials also needs to be understood, while crash damage is harder to detect with carbon fibre.

Meanwhile, the latest 2020 Yamaha engine upgrade got a lukewarm response on Thursday, both riders suggesting it was only a small step in the right direction and that much more is needed,

"We are in a good way, but we need to improve more. It's not the big step we need, but it’s in the right direction," Rossi said of the latest engine.

With Franco Morbidelli second on the timesheets, Yamaha riders filled four of the top five places on day one. Only Honda's world champion Marc Marquez could break the M1 dominance, in third.