Yamaha V4 faces balance issues – Jack Miller raises concerns

Jack Miller has officially begun a new chapter with Yamaha, taking part in the post-race Misano test that saw the YZR-M1 V4 prototype put through its paces for the very first time under his control. The Pramac Yamaha rider ended the session 17th-fastest overall, but his comments revealed cautious optimism as the Japanese manufacturer begins a long-awaited shift in philosophy.

Yamaha’s New Era With the V4

For decades, Yamaha’s inline-four engine concept has been a defining characteristic of its MotoGP machines. Known for high corner speed and smooth power delivery, the inline-four allowed riders like Valentino Rossi, Jorge Lorenzo, and Fabio Quartararo to secure titles and iconic victories. But in recent seasons, Yamaha has struggled to keep pace with the relentless speed and straight-line power of Ducati, Aprilia, and KTM—all of which run V4 engines.

The debut of the Yamaha V4 YZR-M1 marks a decisive break from tradition. After Augusto Fernandez gave the prototype its first race weekend appearance at Misano (September 12–14), Monday’s post-race test offered a clearer look at how Yamaha’s new approach is beginning to take shape. Alongside Miller, factory riders Fabio Quartararo and Alex Rins also tested the machine, giving the engineers valuable feedback from different perspectives.

Miller’s First Impressions

Miller, who joined Pramac Yamaha for the 2025 season, admitted that riding the new V4 was an eye-opening experience.

“It has been very interesting for us to have the chance to do the shakedown of the new Yamaha V4 bike,” Miller said.
“It‘s been a good test to understand both the strong points of the machine and the weak ones, trying to maximize the strong areas and improve the weak ones. We are on the right path: the bike is working well, and in some areas we‘ve already made progress compared to this year’s YZR-M1.”

The Australian emphasized that Yamaha’s engineers face a balancing act. The inline-four’s legendary cornering agility cannot simply be abandoned, even as the manufacturer chases more horsepower and acceleration with its V4 concept.

“Coming from the old M1, whose strongest point was corner speed, we are now trying to find a new balance in terms of geometry, weight distribution, and all those aspects. The bike is doing all the right things, now we just need time, as these are still the very early days of the project.”

The Challenge of Transition

Switching engine philosophy is one of the biggest technical undertakings a MotoGP manufacturer can attempt. Unlike incremental upgrades, building a V4 from scratch requires a complete rethinking of chassis design, aerodynamics, weight distribution, and electronics. The first day of official testing therefore carried symbolic importance as much as technical progress.

Miller admitted that despite finishing outside the top 10 in lap times, his pace was not the main focus. The team’s primary goal was to gather data, evaluate the baseline performance, and begin to map out a development direction. The rider’s experience across different manufacturers—including Ducati and KTM—makes him a particularly valuable asset in Yamaha’s learning curve.

Pramac’s Pride in the Project

Pramac Racing Team Director Gino Borsoi spoke with enthusiasm about the role his team is playing in shaping Yamaha’s future.

“The feeling of this first day with the YZR-M1 V4 prototype was nice from the beginning, because we are starting from a blank sheet of paper,” Borsoi explained.
“For us it is very important to give Yamaha some feedback and our point of view regarding this new project. We know it will be a long journey, but we are very proud to be part of this new challenge with Yamaha.”

The Italian stressed that the opportunity to help build a bike “from scratch” allows Pramac to contribute more deeply than ever before. While the previous M1 was already a well-defined machine, the V4 prototype opens the door to a more collaborative development process.

“Starting from scratch is important for Pramac Racing, because we can put all our effort into developing the bike in the right way. The old YZR-M1 was already a complete bike, but with the new V4 prototype we can provide Yamaha‘s engineers with our feedback to help them. Yamaha now has a huge amount of work to do, and we are ready to do our part.”

Early Signs and Future Hopes

The early indications suggest that Yamaha’s V4 project has potential, but much refinement lies ahead. According to Miller’s feedback, certain aspects already show improvement compared to the current inline-four, but there are still clear weaknesses that must be addressed.

Areas like aerodynamic efficiency, acceleration off corners, and top speed will likely dominate Yamaha’s priorities, as these have been the brand’s biggest weaknesses in recent seasons. At the same time, preserving the smooth handling and stability that have always been Yamaha’s strengths will be critical if the bike is to succeed.

Quartararo and Rins are also expected to provide detailed feedback in the coming weeks, with Yamaha engineers carefully cross-referencing their insights against Miller’s. The combined input will shape the next development steps, possibly including further test sessions before the end of the season.

What It Means for the 2026 Season

While the Misano test marks an important milestone, it is clear that Yamaha is treating 2025 as a foundation year. The true competitive debut of the V4 YZR-M1 is unlikely until 2026, once the engineers have had more time to refine the concept.

Still, Miller’s words—“we are on the right path”—suggest that optimism is justified. For Yamaha, breaking from decades of inline-four tradition was not a decision taken lightly. The fact that early tests already show strengths is a promising sign.

Pramac’s involvement, meanwhile, highlights how crucial satellite teams are in modern MotoGP. By taking on part of the workload and offering constant feedback, Pramac gives Yamaha a broader development base than the factory team alone could provide.

Conclusion

Jack Miller’s first official run on Yamaha’s new V4 MotoGP machine at Misano may not have delivered headline lap times, but it represented something more significant: the beginning of Yamaha’s reinvention. With Miller, Quartararo, Rins, and Pramac all feeding back into the process, the Japanese manufacturer is entering uncharted territory with determination and cautious optimism.

The coming months will be crucial in shaping how quickly the V4 project can evolve. If Yamaha manages to harness the benefits of the V4 while retaining the agility of its famed inline-four legacy, it may yet reestablish itself as a serious contender in MotoGP’s modern power race. For now, Miller’s words capture the mood perfectly: “The bike is doing all the right things, now we just need time.”