Never experienced it myself (until now, maybe) but I've heard of folks having problems with gas caps that had stopped venting. How would one check the cap to see if the vent is working?

 

Your bike stops running.

 

Not sure what bike you have, you could sniff the cap,you should be able to smell the gas.
For example,I have split tanks, left cap not the vented one and no smell but the right one you can really smell it and hear it hiss when I stand up the bike from the stand especially in the sun. Also you can build pressure and leak out the carb or vacuum while riding in cool weather.

 

Actually, I thought the vent in the gas cap was one way. It lets air in to make up for the gas that gets used, but does not let air out.

 

Again, What kind of bike you have will determine it it has vented caps or a vented tank... ????

 

When I saw the title, I figured it was another 'where do you put your gas cap when you refuel' thread.....


On topic, I never had a problem with my cap in 22+ years of owning the bike.

 

If the cap isn't venting vacuum will build up in the tank.
Ride the bike a little and open the right gas cap.
If it is bad you will hear air being sucked into the tank.
The bike will also run like crap if the cap is not venting.

 

Tagging this thread. Interesting that my 2013 Heritage occasionally builds a vacuum but otherwise runs fine-I only notice the vacuum if I remove the cap.

 

You are running EFI.
You don't need to care about vacuum.

 

QUOTE=GraemeR;14203366]Actually, I thought the vent in the gas cap was one way. It lets air in to make up for the gas that gets used, but does not let air out.[/QUOTE]

Yup I've always believed it was one way also. Bike does bog down once in a while which leads me to believe that might not be working hence my desire to test it. The bike is a Softail with split tanks vented on the right, unvented on the left.