I am not sure what the recommended elevation is for 12.5:1 and 91 octane. I can tell you that you can run 87-92 octane in a 2 cycle up to a 13:1 compression ratio at sea level. Sorry I cant be of more help. I ride mostly 0-2000 and when calculating comp ratios and octane we dont have to include elevation change - I would love to understand it better tho!
