reksul, Stallions have the same issue. It appears the newer ones the issue is resolved. They were using a check valve that was not getting the job done. I told that they have changed that valve. Being that MT conversion is the same company as Stallion I would check the check valve. Check with Russel at Thoroughbred Motor Sports of Daytona he is the one who advised me of this issue. My wife's old Stallion would not hold air in the bags, her replacement Stallion does not have this issue. Ted