Can MotoGP’s last inline-four motorcycle survive?

This stuff goes deep.

Anyway, 2021 MotoGP king Fabio Quartararo might say what Slight said, not specifically about Ducatis, but about the V4-powered bikes that now dominate MotoGP.

Yamaha is the only MotoGP manufacturer that keeps faith in the inline-four engine configuration, which has been the backbone of the large-capacity motorcycle market for more than half a century.

Following Suzuki’s exit at the end of 2022, there are just two inline-fours on the grid – Yamaha’s two factory YZR-M1s – which must do battle with twenty V4s, from Aprilia, Ducati, Honda and KTM.

This is a problem for Yamaha.

V4 engines can make more horsepower than inline-fours and V4-powered bikes race in a different way to inline-fours. They focus on maximising their straight-line performance, by accelerating early and braking late, using short, v-type cornering lines.

Inline-four engines contribute to friendlier chassis and cornering performance, so these machines make their lap times by using more corner speed.

However, when you’re riding an inline-four in a group of V4s you will find your usual way through the corners, using more rounded lines, blocked, so you can’t exploit your usual advantage. This is the nightmare that Quartararo is living – the 24-year-old may even have been MotoGP’s fastest rider in 2023 but he finished ninth overall.

Recently the nightmare has intensified, because Yamaha engineers have adapted the M1 to race better with the V4s, which has blunted the bike’s strong points. Yamaha didn’t win a single race in 2023, which is only the third year that’s happened since Yamaha won its first premier-class victory in 1972.

How can Yamaha dig itself out of this hole? The factory has former Ferrari Formula 1 engine designer Luca Marmorini, who also helped develop Aprilia’s current RS-GP engine, working on a new M1 engine, which Quartararo and new team-mate Alex Rins will try for the first time at Sepang, Malaysia, in February.

Will the new engine make enough horsepower? Maybe. In fact some people say the M1’s real weak point isn’t a lack of peak power but rather a too-aggressive power delivery, which causes traction and wheelie problems, which hurt acceleration.

Quartararo’s crew chief Diego Gubellini knows all about these issues, so we asked him about Yamaha’s plans to return its inline-four M1 to the front of the pack.

Oxley: What were the positives and negatives of the 2023 M1?

Gubellini: Generally speaking, the negative points were quite clear – at many tracks we paid a lot in terms of top speed and acceleration.

When we speak about acceleration it’s not only pure power, it’s a combination of different parameters: power, traction out of the corner and the tendency to wheelie, so it’s not a simple equation to increase acceleration. This was basically the main negative point of last season’s bike.

One more thing that’s not really related to our bike, because we can’t say our bike is weak from this point of view, is rideability and turning. Our bike is quite good in these aspects, but these are no longer our strong points compared to our competitors. In the past our top speed wasn’t as good as the others, but we could recover in other areas. Now we cannot, because the other bikes have improved their weak points quite a lot, so now we are similar to them in these areas.

The positive of our 2023 bike was that Fabio found it quite easy to bring to the limit and he knows exactly where and how he can improve.

So the Yamaha is still rider-friendly?

Friendly in that it’s easy for Fabio to understand where the limit is. This is a good point of our bike, also braking is a good point.

Surely, Yamaha looks at Suzuki’s inline-four GSX-RR, which took two wins at the end of 2022, which suggests that the bike would still be competitive now?

First, like I already said, speed and acceleration aren’t just a matter of power, they are a compromise of many things.

In 2022 Suzuki were quite good at finding the best compromise between aerodynamics, chassis balance and engine power. They had very good traction and probably not the best aerodynamics against wheelie but also not so much drag, so this helped their top speed.

There are a lot of parameters that influence each other to generate good acceleration and top speed and this is a big part of the job we are doing this winter to improve our bike. I’m not an engine designer but I know that an inline-four cannot be as strong as a V4, but I don’t think this should affect us in the way it’s penalising us now. Our [overall] performance now is not good as it should be.

All these problems compound each other, because if you don’t have lots of power you can’t run a lot of downforce, so you get more wheelie, which hurts your acceleration further…

In the last few years the manufacturers, especially Ducati, have focused on putting as much power to the ground as they can. To do this you need a lot of aerodynamic downforce. This downforce reduces wheelies, but it also generates a force that pushes the bike out when you lean through corners. This is a fact you cannot change: if you want less wheelie, you must accept to have less turning. True, the Ducati turns better than in the past, but we have followed this general trend and we have lost some turning.

So you’ve gone in that direction because Fabio is always fighting with V4s, which steal his lines and get in the way?

Yes, you are stopped by the other guys, especially in races. If you are behind the others in the corners you cannot use your strong points, so this is another part of the reason why Yamaha and basically everyone else decided to follow this trend [of more downforce for fewer wheelies and thus more acceleration], because if you have a bike that’s completely different in philosophy to the others you can be fast in time attacks but it’s impossible to overtake in races.

Many times last season we saw that Fabio maybe wasn’t the strongest guy in time attacks, because we struggled with pure performance, but in the races he made a lot of overtakes, because we moved in this way, following this trend.

Fabio says he struggles in qualifying and his strongest point is the end of races, presumably because tyres are past their best, so the V4s can’t exploit their horsepower advantage so strongly?

No, for me, it’s more like Fabio’s skills.

To ride with used tyres?

No, it’s difficult to explain. Basically, when you go for a time attack you try to extract everything from the bike, so if you are a good rider, and in MotoGP there are only good riders, you will be close to extracting the maximum from your bike, so your time-attack performance is limited by bike performance.

Then, of course, you cannot do race distance like qualifying. Theoretically, yes, but you don’t have enough focus and energy to do every lap like qualifying. By the end of the race most riders drop their rhythm by maybe 1.5 seconds from their qualifying speed. There are very few riders who are, let’s say, on another level, who drop only half a second. So even if Fabio’s pure performance in qualifying isn’t on the level of, say, a Ducati, he is able to race close to that limit and finally in the race he’s almost there.

So it’s his talent and physicality that make the difference in these situations?

Exactly.

Towards the end of last season it seemed like the Yamaha got stronger – was that really the case or was it a case of some of the tracks helping you?

This was a combination of different factors.

There are some tracks that help us. For example, the straight at Mandalika is quite short, so we don’t pay so much in terms of top speed there [Quartararo had his best result of the year in the Indonesian GP: third, just four tenths off the win].

Then there are some tracks where everyone uses a different rear construction rear tyre. When we go to those tracks where there’s a lot of energy or thermal solicitation going into the tyres the standard tyre wouldn’t be enough to last the race, so we need a specific tyre construction. The change in performance at these tracks is based upon this kind of variation.

Presumably the stiffer construction rear [used at Red Bull Ring, Mandalika and Buriram] gives less grip, so the V4s can use less of their torque advantage, which helps you?

To generate performance you need [corner exit] grip and less wheelie, so if one of these isn’t good you cannot generate acceleration because you have a big limitation. When this limitation is bigger everyone is on same level, so it doesn’t matter if you have a lot of power or not so much power. This is the main point – when there isn’t so much grip it’s a bit better for us.

Also there was a matter related to our approach last season. At the beginning of the championship our expectations were much higher than the reality, because we came from two years fighting for the title until the last races. So when we started the season very far from the top it was a shock for us. Fabio, our crew, everybody, wasn’t ready for this kind of situation and we didn’t extract the maximum in the middle part of the season.

So the lack of results was partly due to a morale situation?

Yes.

We could see that Fabio wasn’t happy at that time.

Fabio, of course, is the main part of the result, but we all work together and often the work of the crew is based on Fabio’s mood. Fabio was stressed by the situation, and the crew, instead of, let’s say, helping him to come out from the situation, also got stressed.

Then you all got used to the situation and started building again?

Exactly.

What are you looking for from the 2024 bike? Obviously horsepower but what else?

During last season our vision changed a bit because in the past we focused on top power. Every manufacturer tries to improve its engine and maybe we have more margin to improve than the other manufacturers, but that doesn’t mean it’s realistic to expect Yamaha to do three years of development in one year.

For this reason our vision has changed. We want to improve in many areas, not only power. We are also working very hard on aerodynamics to improve turning and to reduce wheelies and drag. Also, we are working on the chassis to improve turning and traction. So our picture is that we need a small step in every area to put everything together and generate a big global effect on the performance.