well to start I haven't been on a 250f since 06 but I missed it so much that i picked up a 2007 for cheap. the previous owner ran race fuel in the bike(not sure what octane i think 110) well i ran that true the bike now im back on 93 pump gas and now it backfires like crazy. every time i ride and let off the gas its just a bunch of backfire. how can i make it stop. bike still runs great just back fires alot.