Jack Miller confident in Yamaha’s inline-four despite V4 transition

Jack Miller believes Yamaha's inline-four still has potential as they explore a V4 engine for future MotoGP seasons.

Jack Miller of Australia and Prima Pramac Yamaha rides during the qualifying session of the MotoGP Thailand Grand Prix at Buriram International Circuit in Buriram on March 1, 2025. Photo by Lillian Suwanrumpha/AFP

By Anna Fadiah and Hayu Andini

Jack Miller has reiterated his belief that Yamaha’s inline-four engine still has untapped potential, even as the manufacturer works on developing a V4 power unit to align with its MotoGP rivals.

The Australian, who joined Pramac Racing for the 2025 MotoGP season, remains firm in his stance that an inline-four configuration can still be competitive in modern racing. He pointed to recent championship wins as proof that Yamaha's current engine concept remains viable.

“As I’ve said all along, I think there’s more than one way to skin a cat,” Miller said. “The inline-four was world champion in 2020 and 2021, so there’s no reason to say that they can’t be strong.

“After riding an inline-four, you understand the pros and cons of it. I think the center of gravity is something fantastic about it. Obviously, the width is maybe one of the bigger issues, but being able to put the fuel tank and everything down a lot lower without having that cylinder underneath it is definitely a benefit.”

Miller believes there is still more performance to extract from the inline-four configuration, suggesting Yamaha should not fully abandon the concept as they explore a transition to a V4.

“There are definitely different ways to go around things, and I still believe there’s more to squeeze out of an inline-four than what we’re getting at the moment,” he said. “You don’t need to close doors as well. If you say ‘we need that,’ that is not the way to work.

“I think Yamaha are approaching it in a good way, trying to understand all the circumstances before making a decision.”

Yamaha’s experience with inline-four still valuable

Miller emphasized that Yamaha’s extensive knowledge and experience with the inline-four engine should not be overlooked.

“They’ve been working with this project for so long, they have a wealth of knowledge of the inline-four engine,” he said. “To say one way or the other is silly because in racing, it’s like that. Everybody sees someone doing one thing for two years in a row, and everybody follows like sheep.

“It’s the same with the Boscoscuro-Kalex situation in Moto2. It’s what happens.”

For Miller, Yamaha’s challenge is not about completely overhauling their engine philosophy but rather refining their current package while methodically developing a competitive V4.

Time is key for Yamaha’s MotoGP resurgence

The 2025 season marks Miller’s first year as a Yamaha rider, and he believes the Japanese manufacturer already has the right elements in place.

“All Yamaha needs is time,” Miller said. “That’s it. They’ve got all the pieces of the puzzle, they just need time to slot them all together.

“We’re chasing tenths here, not seconds. They’re so close but so far. The hardest ones to find are those last few tenths.”

Miller also praised Yamaha’s testing efforts, particularly with the additions of Augusto Fernandez and Andrea Dovizioso to their development team.

“They’re busting their arses, with Augusto and Dovi as well, and even Cal [Crutchlow] when his hand sorts itself out,” Miller said. “They’ve got a fantastic squad there in terms of trying to work, develop, and bring us stuff.

“I would possibly say one of the best test teams around. The wealth of knowledge with Dovi, and then the youth and keenness of Augusto – I feel like he thinks he has unfinished business here, and that role as a test rider is like his way back in. So, he’s trying to give it his all.

“You’ve got those two working together, and that’s helping the project as well. So, they’re ticking all the right boxes and doing all the right things. It’s just a matter of time, basically, until it all comes together and they get back to where they belong.”

Miller treated like a factory rider at Yamaha

Despite being part of the satellite Pramac Racing team, Miller says his role within Yamaha is equivalent to that of a factory rider.

“[It’s] pretty much identical in terms of parts, in terms of test items, everything,” Miller said, referring to his status compared to Yamaha’s factory team riders, Fabio Quartararo and Alex Rins.

“The way that Yamaha – from a company that was quite closed in the past with what they did in terms of factory riders and satellite riders – they’ve turned a new leaf completely, and it’s an open slather, you could say.

“We structurally worked through the whole test plan throughout the whole testing program. Whether I try a chassis and it goes over the different days through all the riders to try to gain information from everybody, it helps us improve for the next step.

“I think they’re doing it the correct way, and it shows their full commitment to improving the project and their position.”

With Miller confident in Yamaha’s approach and committed to maximizing the potential of the inline-four engine, the coming races will be crucial in determining whether the Japanese manufacturer can close the gap to their V4-powered rivals.