Motorcycle Repair: pressure relief / vent, ultra groundpounder, vent tube

Question
My bike is a 2000 Ultra Groundpounder with an S&S 113. I have a vent tube from the top of the left tank that runs down thru the battery box. There is a valve that the tube connects to, another hose connects to the other end and down. This valve was complketely plugged with old gas that had gummed. I cann't tell if this is a one way valve or what but it is my vent and or pressure relief. I have taken it everywhere and no one knows or has it.The only thing stamped on it is a number 30. The valve is black about 2 1/2" with a short nipple on one end with a larger hole than the other which has a little longer nipple. Thanks

Answer
I dont know to much about Ultra's but your valve is either a overflow or a vent. usually the gas cap has the vent, but they might have done somthing different.
Since we can assumn that this is the vent for the gas tank, the one way should be in, so you are not creating a vaccumn in the tank. I have never seen one of these valves so I can't comment on what to use. It sounds to me like you are on the right track.
You might want to contact the company that built the bike direct and see what their take is on the problem.
I hope I helped
Mike