There has been a lot of discussion on Trials Central about all of the damage and possible solutions to the ethanol problem especially in small engines in the past. Type in ethanol in the search bar and you can get all you need to know about the ethanol problem. Many of your fellow competitors in D-4 have switched over to avgas 100 both with and/or without stabilizer added. Pure gas has not been obtainable in D-4 for more than a year. The largest Trials bike dealer in the district has been using Avgas 100 for a couple of years with excellent results. I have been using avgas 100 with stabil for some time for all of my small engine equipment (bikes, lawnmower, ORV, etc). It is available in all of the big box stores and car parts stores in the Rochester area. Starbrite is another possibility and is also available in the stores mentioned. You will save yourself a lot of time and expense maintaining your bikes if you stay away from ethanol based gas.