MotoGP: Yamaha explains Mugello engine failures
Rennie Scaysbrook | June 2, 2016
Rossi’s stricken M1 is carted back to the Mugello pits.
The engine failures on both Valentino Rossi’s and Jorge Lorenzo’s Yamaha YZR-M1 MotoGP machines at Mugello was caused by the electrical rev limiter allowing too high a spike in revs at the crest of the front straight, resulting in the piston hitting the valves, it has been revealed.
“After the technical problems in Mugello the two defective engines were returned to YMC for investigation,” said Kouji Tsuya, project Leader for the 2016 Yamaha YZR-M1. “Following our detailed investigation of the engines, telemetry data and related systems we found the cause of the failures. The failures were caused by an electronic issue related to the rev limiter which ultimately resulted in valve and piston damage. The cause for both Jorge’s and Valentino’s engine failures was the same. To be clear, there was neither an engine component nor a structural failure, it was purely an electronic control issue.
“Valentino‘s failure was caused by an accidental over rev in acceleration that occurred jumping over a crest with full throttle at the end of the straight. This failure was not in any way related to the mistake made by Valentino at the San Donato corner on the lap before.
“There were no special mapping settings used for Mugello; we used the same precise mapping as always. We have now withdrawn both engines from the allocation for the season.
“We have a strong history of engine reliability and this fact does not change after this incident; the engines had no problems, but we were not aware of the different behavior of the standard ECU software, that made the rev limiter work in a different way compared to last year. We set the rev limiter using last year‘s data in exactly the same way as we did last year, but we could not be aware that the software worked in a different way.”
