At my wits end. Will not start, has spark, getting fuel, (gas is new and runs in other atv) will turn over and makes a "fart" sound if that helps. Battery tests good, put in a different battery and it does the same thing. Been told it might be bag rings but the plug isn't oily or anything. It has @ 2200 miles on it. was running fine and the out of the blue will not start any idea? thanks