Where's my tank vent?

[Wtlj]

Hi folks, I have a 2003 sportster 1200. I purchased it with a lot of custom parts on it including a indented and shaved peanut tank. Am I supposed to have a tank vent or is that the job of the vented cap? I recently purchased a new pop up cap from harley and haven't installed it yet.
I've had issues with paint peel on the outer edge of bung from vapors escaping between the cap gasket. This got me thinking if the tanks building up too much pressure and escaping in the wrong spot. The only line coming out of the tank is the fuel line to the carb. When I remove the gas cap I can hear air releasing from the tank, is this normal?
Any help is greatly appreciated.

 

[Jack Klarich]

Here is a stock tank, note the vent line and valve

 

[Wtlj]

Yes, I don't have a valve like that. I have a pingle valve fitted to the rear of the tank. So do I need another vent other then a vented cap? My uncle rode the bike for the past few years with no problems. Just got to thinking today about it!

 

[Jack Klarich]

If you have a vented cap that should work, if you have pressure or a swoosh sound when you open the cap you will need more venting

 

[Wtlj]

Yes, I definitely have a swoosh sound! I'll see how it is after the new caps installed. What options do I have for more venting?