one of my quads is an AC 650 V . recently i removed the gas cap and the rush of air almost blew the cap from my fingers.i was told that most likely that the vent line was pinched off. but what i found was that there is a check valve in the line that only lets air in . i replaced the check valve with a in line filter that will let air go in and out with out restriction.
has any one besides me ever had this problem?