Fabio Quartararo tested Yamaha’s official new V4 M1 bike on Monday, and he has been honest about it. At the moment, it does not fix the team’s problems. After trying it at Misano, following a private test in Barcelona, he admitted he actually feels worse on the V4 than on the old inline-four motorcycle. In the Misano morning test, he finished only 17th, more than a second slower than Alex Márquez. Barcelona gave him some hope, but Misano showed that there is still a lot of work to do.

So what is the problem?

The biggest issue Quartararo sees is in turning and handling. The old inline-four Yamaha was known for being very good through the corners, with a strong front-end feel. The new V4 has lost some of that. He says it struggles more in areas with quick back-to-back corners, such as Misano, where the bike feels aggressive and harder to control.

Another problem is with electronics and power delivery, as they are not yet working correctly. The bike does not give smooth or predictable power when coming out of slower corners, and braking is still weak. Quartararo has often said Yamaha must improve its rear-end grip and braking performance, because rival bikes can brake harder and later, which makes racing easier for them.

Confidence is also missing. Quartararo explained that he cannot fully trust the bike yet because its behaviour changes depending on the tyres, grip level and track layout. Without that trust, a rider cannot push to the limit.

So if there are so many problems, why did Yamaha switch to a V4?

Yamaha decided to move away from the inline-four engine because they felt it had reached its limit. Other teams now use V4 engines, which are usually better for aerodynamics and top-end power. By building a V4, Yamaha hopes to open a new era of development, something no longer possible with the older design.

There is also hope that they will gain more straight-line speed, which has been one of Yamaha’s main weaknesses in recent years. A well-developed V4 can also give better stability under braking and better traction out of corners. Yamaha believes there is still room for improvement, but that will take time and many more tests.

Could the V4 alone fix Yamaha’s problems?

According to Quartararo, the answer is no. He has said several times that the engine change on its own will not make Yamaha competitive again. The team still has problems with chassis balance, electronics, grip and aerodynamics, and all of these must be improved together. In fact, he points out that the V4 has not yet solved the same old problems that Yamaha already had with the inline-four.

This means Yamaha must be careful. If they chase more power and speed but lose the cornering strengths of the old bike, they could end up being even worse. Quartararo wants to see an upgrade package that combines the best of both worlds, keeping Yamaha’s famous agility while adding the extra speed, braking stability and acceleration that a V4 should be able to offer.

To achieve this, Yamaha must do much more testing in different conditions. At smoother tracks like Barcelona the bike can look better, but at more demanding circuits like Misano the weaknesses become clearer. Yamaha needs to fix the way the bike handles fast corner sequences and improve its balance on different tyres and grip levels.

The chassis and aerodynamics must also be refined around the new V4. The shape of the bike, the frame, the suspension, all must be adjusted to suit the new engine layout. Above all, Yamaha needs to give Quartararo confidence that the bike will behave the same every lap, no matter the conditions. Without that, he cannot push to the limit.

However, they are working with limited time. The full V4 project is aimed at 2026, but development windows are restricted by MotoGP rules. Yamaha must use every test to gather data and improve the bike, or they risk falling further behind everyone else.

So while the Yamaha V4 is a bold move, it is certainly not a quick fix. Fabio Quartararo’s feedback is clear: right now, the bike is worse in key areas, and the engine change alone will not make Yamaha competitive.

Still, the potential is there. It only depends on whether Yamaha can hold on to the strengths of their old inline-four while adding the speed, braking stability and traction that a V4 can offer. If they succeed, the new M1 could put them back in the fight. But unless they act quickly and solve problems across the whole bike, there is a real risk that their rivals will continue to leave them behind.