Yamaha has withdrawn its request to unseal the engines to replace internal components which they believe caused issues for Maverick Viñales, Valentino Rossi, and Franco Morbidelli at Jerez. Yamaha had made a formal request to the MSMA, the MotoGP manufacturers' association, to open the engines and swap out defective parts.
Initially, the suspicion fell on sensors inside the exhaust port, but it is now believed that the problem was caused by the valves. Yamaha had set out its reasons to make the change in its submission to the MSMA. Under the technical regulations, the manufacturers are allowed to unseal the engines to replace parts only if they can get unanimous permission from the other MSMA members, and that such a change does not confer a performance advantage and is necessary on safety grounds.
That is where Yamaha's case appears to have fallen down. The other manufacturers were not convinced by Yamaha's explanation, and asked for more information to be able to make a decision on approval.
This put Yamaha in a very delicate situation. They would have liked to change out the parts, but to get permission to do so, they would have had to reveal a level of technical detail which could have given away too much information to their rivals. Instead, Yamaha have decided they can manage the rest of the season on the engines they have.
The fact that the Red Bull Ring was the toughest track for engines left on the calendar may have influenced their decision. After Spielberg, the factories face the front straight at Barcelona once, and a double header at Aragon, though Aragon's fast back straight is downhill.
Yamaha's predicament is in part a result of the dysfunction inside the MSMA. The manufacturers' association has long been unable to agree on anything, with the disagreement between Ducati and the other manufacturers at Qatar 2019 over their use of the rear swingarm spoiler being the final breach. With no goodwill between manufacturers, they are not inclined to give each other any leeway in situations such as this.
Naturally, this is likely to come back and bite the other manufacturers in the future. If another manufacturer suffers a similar issue to Yamaha in the next few years, and it is a factory which denied Yamaha's request, Yamaha are likely to treat them in exactly the same way, and deny a request to unseal engines.
Yamaha must now juggle their remaining engines for the rest of the season. Three engines have been withdrawn for allocation: 1 each for Rossi, Viñales, and Morbidelli, all three having suffered issues at Jerez. The engine in bike which was involved in the crash between Franco Morbidelli and Johann Zarco has not been withdrawn: the engines are designed to withstand crashes, but the extreme temperatures at Jerez may have put the bikes outside their operating limits. That leaves Rossi, Viñales, and Morbidelli with four engines for the remaining ten races, and Fabio Quartararo with five.
The engine lists to be published by Dorna on Sunday morning may reveal a little more. However, the engine lists only track whether engines ARE used, not whether the CAN be used. Only in the next few weeks will we learn whether Yamaha will use them for the races, for practice, when there is least to lose, or leave them crated as a back up option in case one of their other engines fails.
In an interview with the MotoGP.com website, Lin Jarvis explained Yamaha's decision. "We made a request a week ago to replace some valves in the engines that we had stopped using since the two failures we had in the Grand Prix 1," Jarvis said. "We were then requested to provide more specific evidence, both from the manufacture of the valves and also the specific properties of the valves."
In the week since that request had been submitted, Yamaha had understood much more about the cause of the failures experienced at the first race in Jerez. "During the one week since, we investigated deeply inside the factory and also we are in contact with our vendor and finally we were unable to provide the documents that were required and requested. And also at the same time we discovered much more about the valve issues that we had. So finally we withdrew. It was a very short meeting yesterday in that sense because we formally withdrew our request."
Jarvis said they had worked out a way of managing the situation with the engines unchanged. "We will manage the situation. We are completely confident that we can manage without any safety issues on the track. We will do that by a combination of changing engine settings and also managing the rotation of engines throughout the seasons."
What is to be understood by "changing engine settings" is uncertain, but there are continuing reports that Yamaha has been forced to reduce the revs on its engines.