Is Yamaha’s upgrade really an improvement? Jack Miller said bluntly: “Not very impressive!”

Jack Miller, the veteran Australian rider currently with Pramac Yamaha, offered a blunt and honest evaluation of Yamaha’s latest engine upgrade, tested during the post-race session at Aragon. While Yamaha hoped for signs of progress in their quest to catch up with frontrunners Ducati and KTM, Miller revealed that the upgrade was not revolutionary.

“The engine upgrade is not huge, to be honest, but it’s still an improvement,” said Miller. His words reflect the reality of Yamaha’s technical challenges in MotoGP. Rather than touting the upgrade as a major leap forward, Miller praised it only as a small step in the right direction.

Engine Upgrade Brings Limited Gains

Yamaha introduced a revised engine configuration to address issues related to throttle response and mid-corner acceleration—areas where they’ve notably lagged behind Ducati and KTM. However, Miller made it clear the improvement was only modest. “It was an improvement, sure. But not a game-changer,” he admitted. For a manufacturer under immense pressure to deliver meaningful changes, this lukewarm feedback places further urgency on their 2025 development program.

Addressing Vibration Issues Was a Quiet Victory

Beyond the engine tweaks, the Aragon test allowed Yamaha to tackle a major issue that disrupted both Miller and Miguel Oliveira during the race weekend: unexplained vibrations during acceleration. These issues cost the team performance during both the Sprint and Grand Prix. “After the race, we went straight into diagnosing the vibration problems,” Miller explained. “It was nice to clear that up. We found what was causing it, and that will help us for the rest of the season.”

New Swingarm and Aero Parts Under Scrutiny

In addition to the engine work, Yamaha also gave Miller a new swingarm to test, along with a revised aero package. The goal was to improve rear-end feel and stability under braking—two key areas Miller has been requesting support in. “We did comparisons between the new and old swingarm. Worked on the traction control. Overall, the feeling was good,” said Miller. While not all upgrades will immediately make it to race weekends, the data collected is critical for Yamaha’s development timeline heading into the second half of the season.

Barcelona Test Looms as Critical Milestone

With the Catalan test in Barcelona scheduled to follow shortly after Aragon, Miller is already focused on what lies ahead. He and teammate Oliveira, alongside Yamaha’s test riders, will conduct two full days of testing at the technical and demanding Circuit de Barcelona-Catalunya. This circuit is particularly valuable due to its combination of low-grip corners and long straights—providing a thorough challenge for both engine performance and handling. “We’ve got a day off then we’re back on the bike in Barcelona,” Miller stated. “It’s a track where we suffer on the long corners, so it’s a good place to test.”

Yamaha’s Eyes Set on Mugello for Full Rollout

Pending the outcome of the Barcelona test, Yamaha intends to bring the best of their upgrades to the Italian Grand Prix at Mugello. A high-speed track with sweeping curves and heavy braking zones, Mugello demands the absolute best from any MotoGP machine. If the upgrades show consistent results during Barcelona testing, fans can expect Yamaha to debut a fully revised package. “If Barcelona goes well, Mugello is where we’ll see what we’ve really got,” a team source suggested.

Why Small Gains Matter in MotoGP

In the world of MotoGP, massive leaps in performance are rare. Instead, the journey is often defined by incremental improvements. Yamaha’s approach—addressing specific weaknesses like vibration and electronics before introducing aerodynamic and engine updates—mirrors this philosophy. Jack Miller understands that process all too well. Having raced for Honda, Ducati, KTM, and now Yamaha, he knows that rushing unproven components into races can often do more harm than good.

Miller’s Experience Adds Value to Yamaha’s Development

Miller’s extensive MotoGP background adds significant value to Yamaha’s development process. His ability to draw comparisons across manufacturers gives engineers a clearer picture of what works and what doesn’t. “I’ve ridden a lot of bikes. When I say something’s working or not working, it’s based on more than just feel—it’s experience,” Miller explained. Yamaha’s engineers reportedly appreciate Miller’s candid feedback, which helps them avoid costly missteps in development.

The Ducati and KTM Benchmark

Miller’s previous stints at Ducati and KTM make his current Yamaha role even more important. Both of those manufacturers have made rapid progress in recent years, with Ducati dominating the grid and KTM rising to consistent podium contention. “You look at Ducati and KTM—they’re innovating fast. They test, fail, improve, and race,” Miller noted. Yamaha, on the other hand, is still catching up. But Miller’s experience with their competitors gives them a roadmap.

No Time to Waste: Barcelona and Mugello Must Deliver

While the Aragon test was a decent start, Miller and Yamaha know that real answers will only come after the Barcelona test and, ultimately, Mugello. The team cannot afford to delay development if they hope to make a dent in the championship standings—or even catch Aprilia in the factory constructors’ battle. With Toprak Razgatlioglu also joining Yamaha in 2026, the factory is under even more pressure to deliver a competitive bike before next season.

Oliveira Also Feeling the Heat

Meanwhile, Miller’s teammate Miguel Oliveira is under intense scrutiny as well. With his seat potentially on the line due to Toprak’s arrival, every race and test session could be pivotal in deciding his future. Oliveira echoed many of Miller’s sentiments, noting that the bike is improving slowly but needs more fundamental changes to be truly competitive. “This bike is not easy to learn,” Oliveira admitted. “But we’re working hard. The Barcelona test is crucial.”

Will Mugello Be the Turning Point?

Yamaha fans are already circling the Mugello weekend on their calendars. While Barcelona will provide data and development, Mugello is where upgrades get tested in combat. If Yamaha can show real race pace improvements there—especially in qualifying and acceleration—it will be seen as proof that the recent changes have paid off. Miller is cautiously optimistic but knows that the proof is on the track, not in simulations. “Talk is cheap in this game. Let’s see what we can do when it counts,” he said.

Conclusion: Yamaha’s Long Road to Redemption Begins Now

Jack Miller’s honest critique of Yamaha’s Aragon engine upgrade shows that while progress is being made, the journey is far from over. The improvements are real—but they’re small, not seismic. What matters most now is what Yamaha does with that data in Barcelona and whether they can turn modest steps into meaningful results. The challenge ahead remains steep. Ducati and KTM aren’t slowing down. But with experienced riders like Miller providing grounded feedback and engineers responding with precision updates, Yamaha might just be laying the groundwork for a stronger second half of the season.