Join Date: Jun 2011
Location: East Central Iowa
Several things could be causing your problem, one of which, taht many people forget is the speedo/odo calibration. Have you checked the miles recorded vs mile markers or better yet by GPS?? I temporarily hung my GPS on the bike, showed I was off by 5% across the board.
My TTS tuner allowed me to change the speedo calibration, not sure if the Thundermax does or not.
Unfortunately I know nothing about the thundermax, but there has to be a way to lean down the mixture in the highway cruise ranges, that's where most of your mileage will be gained.
My last 3 bikes have all been similarly tuned, and all got in the 38-42mpg range depending on how I rode them. 35mpg would upset me too.
2015 RGU CVO........under continuous change......