Can someone explain to me the difference between a vented and non vented gas cap? I have a flush mount pop up that will not fit my tank. Seems to be bottoming out on the vent tube that is in the fuel fill. In looking at the gas caps is there a noticable difference between vented and non-vented? Thats my Dumb question of the Day. Thanks

 

I checked some previous threads. Looks like most recent responses aren't very reliable.

This video is pretty good.

Friction Girl Mechanics - Vented and Non Ventilated Gas Caps:

 

Your tank has two vents, stock cap is vented to let air in but not out.
There is another vent on the tank to let air out, both work together so no gas is spilled if the bike is dropped, also allows for expanding gasses in tank.
Non vented is like a bottle cap, builds up pressure or creates vacume, depending on condition, so needs two way vent on tank.

 

You have the wrong gas cap. Sportster caps are smaller (not as deep).

 

Thanks for the reply. the cap sits about a quarter inch above the tank. Makes sense.

 

Looking on JP Cycles sight at caps for Sportsers, they look very shallow.