Yamaha’s 2023 YZR-M1: last chance for the inline-four?
Quartararo tests a 2023 YZR-M1 prototype, with increased downforce aero, at Valencia last November. Will it be enough to take the title back from Ducati?
The inline-four MotoGP bike seems to be in danger of extinction. Nine years ago, when Suzuki replaced its GSV-R V4 with its inline-four GSX-RR, the MotoGP grid featured eight inline-fours, alongside 16 V4s, so a full third of the grid.
This season there will be two inline-fours and 20 V4s.
So, how long before the grid is all V4-powered MotoGP bikes, just as it was during much of the last two decades of the 500cc world championship?
The question of the inline-four’s future in MotoGP may be answered this year, by Yamaha’s latest YZR-M1, which is fighting a rear-guard action for MotoGP’s longest-running configuration, which won its first world championship in 1950 (with the seminal Gilera Quattro) and its last in 2021, when Fabio Quartararo won the M1’s eighth riders title.
Horsepower is doubly important now, because it makes you faster around corners as well as down straights
If the 2023 M1 is a success, Yamaha will continue with this configuration. If it isn’t the company’s MotoGP project leader Kazutoshi Seki has already stated that he will consider building a V4 instead.
This blog has already explained the basic positives and negatives of MotoGP inline-fours and V4s. To sum up in one sentence: inline-fours handle better because their longer crankshafts stabilise the motorcycle, while V4s make more horsepower because their shorter, stiffer crankshafts allow more high-rpm performance.
And horsepower is doubly important now, because it makes you faster around the corners as well as down the straights. If you have power to spare you can deal with the extra drag caused by more downforce aero, which creates improved braking stability, generates more cornering grip and reduces wheelies.
Given an empty racetrack, inline-fours can be faster, using their arcing, U-shaped cornering lines to generate massive corner speed. However, this is difficult to achieve while battling with V4s, because V4s are faster on the straights and their cornering dynamics encourages them to use V-shaped lines, so they can dive straight at the apex and get in the way of the inline-fours.
Yamaha’s inline-four M1 engine – note crankcases machined from solid to increase rigidity – uses the same basic concept as the Gilera four, which won the 1950 MotoGP world championship
Of course, inline-fours have won two of the last three MotoGP titles and Suzuki’s GSX-RR won two of the last three races of 2022, so the layout isn’t necessarily finished. And yet, consider Álex Rins’ victories at Phillip Island and Valencia – corner speed matters more at Phillip Island than anywhere else and at Valencia Rins managed to lead from start to finish, so he had an empty racetrack throughout.
This year Suzuki is gone and Yamaha has gone from four bikes to two – and the fewer inline-fours on the grid the harder it gets for inline-four riders, because they are racing against more V4s that are better in the battle.
This is why Yamaha has been working to make its M1 work more like a V4, via downforce aero and different geometry, so its riders can fight with their V4 rivals. And this is why the M1 is no longer the neutral, effortless machine it once was, so it needs to be manhandled more like a V4, which is what Quartararo does.
“Everyone thinks the Yamaha is a smooth bike, but not any more,” says factory test rider Cal Crutchlow. “You used to be able to ride it with one hand and you’d have rookies on satellite bikes getting podiums, but now Fabio is the only guy who can get the most out of the bike because it’s more aggressive. That’s a combination of geometry, downforce aero and so on. And by the way, I’m a firm believer in downforce aero because at 200mph it’s safer with the front wheel on the ground.”
While Quartararo has been able to get the maximum out of the point-and-squirt M1 during the last couple of years, Yamaha’s other experienced riders – Valentino Rossi, Franco Morbidelli and Andrea Dovizioso – have scratched their heads, wondering why the M1 is no longer the friendly beast it used to be.
Quartararo, with crew chief Gubellini and Takahiro Sumi, general manager of Yamaha’s motorsports development division, to his left, after his superb second place at Red Bull Ring last August
If the 2021 MotoGP champion had had another ten horsepower last year he probably would’ve successfully defended his championship. Yamaha engineers calculated he lost between two- and four-tenths of a second per lap due to poor acceleration and top speed, so their big focus for 2023 is to regain at least some of that time.
But can Yamaha do it? The company has hired former Ferrari Formula 1 engineer Luca Marmorini to bring some F1 magic, but even F1 engineers are subject to the laws of physics. Marmorini’s job isn’t just increasing power by conventional tuning, it’s getting around the problems of the inline-four’s wider crank which can become unstable at ultra-high rpm, causing crankshaft vibration and valve float.
Obviously Suzuki found something last year, because the GSX-RR usually had more top speed than the Yamaha, but not at Valencia, where Rins never had anyone to slipstream. The average of his five best top speeds during the last race was 202.3mph (325.8km/h), against Quartararo’s 203.8mph (328.2km/h). Fastest, of course, was a Ducati (Enea Bastianini’s) at 208.6mph.
Marmorini has definitely found something, but will it be enough to beat Ducati’s dominant Desmosedici?
“The new bike is fast – you can definitely feel the difference, pretty much everywhere,” adds Crutchlow. “Top speed is the main thing they’re looking for and they’ve done a much better job on that. The big thing now is corner exit, because the Ducati is so strong on the exit of the corner – they just go.”
Perhaps Yamaha should hire a Suzuki engineer or two…
Yamaha’s 2023 front end – this is why the M1 needs more power, not only for more speed, but to allow it to run more downforce aero for better cornering grip
Quartararo’s crew chief Diego Gubellini has already found better corner-exit performance from the M1, using the benefits of downforce aero to change the bike’s geometry for better acceleration, so what else has he and Yamaha got in store for 2023? We asked him at Valencia…
Oxley: We saw Fabio struggling with a lack of power throughout 2022 – would you blame that for some of his mistakes, like his crash during the Phillip Island race?
Gubellini: To ride with the other guys Fabio is very much on the limit, riding without any margin, basically. And if you are over the limit at every corner on every lap then it’s easy to make mistakes. So, yes, the Phillip Island crash happened because he was riding over the limit.
During this season we learned that at many tracks where in the past we were very strong that it’s not like that anymore, because Aprilia and Ducati have closed the gap in the turning ability of their bikes, so now we are fighting with the same turning performance but with less power than them. Like here at Valencia there are a lot of tight corners, which was an advantage for us in the past, but now not really, so it’s not easy.
Your main aim for 2023 is more straight-line performance, so how’s that going?
We’ve found some improvements in speed and acceleration. We are trying hard to get a better engine but it’s not a one-day transition, it’s something that needs time. That’s why at every test we’ve tried to bring some parts to improve power. After this race and test we will have some more details to try in that area.
How much more power do you need for 2023?
I cannot say exact numbers but compared to 2022 we need much more – we need a big step!
We estimate, depending on track layout, that we lose between two and four tenths per lap with the 2022 engine, so this is something Fabio needs to compensate for in his riding. For sure this is not easy for him, so we need a big step.
Crutchlow tries new seat aero at Valencia. The winglets increase rear load during braking and mid-corner but can increase wheelies – it’s all a balance
Do you think you can make enough power from an inline-four?
I think it isn’t only engine and power, I think it’s more complex than that, because the riding style we need with our bike isn’t only related to the engine. It’s, let’s say, the DNA of our bike, combined with Fabio’s riding style, so we are trying to figure out how to improve this part of our performance.
There’s also the chassis, aerodynamics and so on, so there are a lot of things that can improve the pure performance of the motorcycle and how to get that performance.
There are many things we need to improve to be competitive in the fight and we are trying to figure out how. It’s not only the engine. We need to investigate and explore different areas.
So you don’t think engine layout plays a part?
It’s partly related to the torque delivery but weight distribution, chassis stiffness and aerodynamics also play a part. Lots of things are connected!
Basically, our strategy for 2022 was to improve the power but because the improvement was very, very small we tried to improve acceleration in other ways.
Not all the parts where we can make more power are sealed, for example the throttle bodies and exhaust, but we can also improve this area of performance by better turning, better exit traction and less wheelie, via the wings, so working on all of these factors actually helped us improve the acceleration area. Like everything in MotoGP, it’s a combination of many things.
The big thing in MotoGP now is stopping the bike and turning it fast, so the rider can lift up the bike to use the rear tyre’s larger contact patch to open the throttle harder and sooner, so it’s no longer about big, arcing cornering lines…
I think that during the last few years the riding style and how to perform in MotoGP has changed quite a lot, because we’ve introduced a lot of downforce. This helps the bike to turn [because more front load increases front grip]. Also, because we have much more downforce at the front we can use different static weight distribution to also improve rear grip. Now the front is more down so we can push the rear down more [for more rear grip].
Also there’s the ride-height device, which reduces wheelies, so we are much more at the limit of everything – of tyres, of let’s say human performance, and for that reason the difference between all the riders is much smaller.
Perhaps the biggest problem, especially for you, is that there are eight Ducatis on the grid, so can an inline-four be fast enough to get away from them?
I don’t know yet. As I said, there are many things that can improve our speed – engine power and many other parts. But now we first need to check how much we’ve improved for 2023 and the next step check is to see how much our competitors have improved, because if we improve but they keep the same performance gap then we will be in the same situation.
We’ve heard you’re working on four different engine specs for 2023…
Not really four different specs. We decided to develop in several different directions and now we are trying to finalise the final version for 2023, trying to combine all the good things together, but there aren’t really different engine specs.
You’ve changed the weight distribution of the M1, so maybe that’s why Quartararo’s style is so different now – he’s amazing to watch, manhandling the bike, so unlike Jorge Lorenzo when he won the 2015 title on the M1.
With our bike we need to ride like that because we perform better, but the good point of Fabio is that he can brake really hard and at same time carry a lot of speed into the corner. Also during the first acceleration phase, from the edge of the tyre to the pick-up area, he is quite strong, so this is where he is better compared to the other Yamaha riders.
It’s true that when we are fighting with other bikes, especially like at the last few races, we cannot ride the Yamaha in the old way, because the Ducatis can easily overtake us on the straight and then they can stop us in corners. For that reason the first step is try to reduce the gap in top speed and also to learn how to perform more like our competitors. This is a process we are going through – changing the bike a bit and changing Fabio.
So you are trying to make the bike corner with V-lines more than U-lines?
Yes, but it’s not something that you can change in one day.
Yamaha introduced a new chassis late in the season, was this part of the process?
Fabio used this chassis after Misano [in September]. Actually the difference is very, very small. The performance is very similar, it’s just a matter of feedback – it gives Fabio more feel from the front in heavy braking. The difference in performance is very small but we decided to go in that direction, knowing that braking is so important for us.
Aprilia and Ducati are using more downforce aero than anyone – diffusers and ground effect fairings. We know that the Japanese factories aren’t keen to go in this direction, because there’s no direct link to street bikes, but surely you have to go this way in MotoGP?
This is something that people who watch races on the TV sometimes don’t really understand: having a powerful engine isn’t only about top speed. It lets you decide the amount of downforce aero you can use, because of course the extra drag costs you some top speed, but with more downforce you gain a lot of grip and you have less wheelie, so finally your overall performance is better. That’s why we need more power to decide how to optimise this aspect of the bike.
So, will you use a ground-effect fairing for 2023, because it generates less drag than diffusers, but still pushes the tyres into the ground for more grip?
This is the thing that we are trying to develop for next season but we don’t know when we will be ready for this kind of aero package. For sure this is something we must do because we are really missing something in this area.
AUTHOR Mat Oxley