I can't seem to bleed the air out of the radiator overflow tank line. I tried filling the the radiator to the max and blowing the coolant (thru the air vent line while the coolant tank filler cap was closed) back up to the radiator, then capping the radiator at the same time. Started the bike and when it warmed up, the same air bubble came back at the radiator entrance (the highest point in the line). When it cooled down, the air was sucked back into the radiator. Any suggestions.