At the recent U.S. Grand Prix, where we had a wildcard entry, we had to run the regular GP fuel, 100 octance low lead, which is an avgas. The representatives from ELF told us they would help us with the settings of our engine. They said that the fuel was "very fast" burning, and to go out in the first practice session with our regular settings. We ran the session, then pulled the head off and got one of the ELF people to look at the piston... He located an ELF engineer to inspect it and he told us to go down two main jet sizes, one pilot jet size, and move the needle to the middle position and give it a try.
After the afternoon session we again pulled it down for inspection and
the ELF rep got the team manager from Muhlebache Honda, a Swiss racing team to look at it. He recommended to go back up one main jet size, move the needle up one notch, and turn the pilot screw in 1/3 turn and go for it. After the next session the next morning, we pulled it down again and the ELF guy looked at it, told us to hold on, went and got a guy from an Italian 125 team, showed the top of the piston to him and said, "this is what perfect looks like." It's funny, but we thought it was detonating, but it ran perfectly for the GP.