got all nervous before headin out and tried a strap wrench. Easy piezee.
That won't stop me from replacing the stock cap, which is def. not venting.

 

Channel locks and a rag.

 

UPDATE; since I posted this, I found that when replacing the gas cap. You should tighten till it clicks. Than back it all the way out before it unthreads.
Doin this allows the necessary space for pressure to escape. I think?
Just know that doin this every time now, allows for easy gas cap removal.

 

Your Softail unless it was made for CA has a vent coming off the front running down by the forks and back thru the trough under the tank. It exits just in front of the rear wheel. You can see mine in the attachment ending just above left shock. There should be no pressure and this is the vent. The cap vents in but not out. You might want to talk to the dealer. There were quite a few bike back a few years ago that had a neck problem in the tank from welding. There was a fix for this and a special tool.

 

Yesterday my gas cap on my softail got stuck. Tried every thing to get it off. Channel locks, sprayed a little wd-40 around the cap. Nothing would work. I had my friend look at it he couldn't get it of so I took it to my dad who is a Harley mechanic and he couldn't get it off. We ended up having to drill a hole in the cap and carefully cut it off.

 

from the day when I originally started this thread, I was really in a bind with mine.
My last resort was a strap wrench, which worked perfectly.
Started to use the technique I now use regularly with constant success.
@RIPSAW; I saw the vent tube when I did my tank lift early this year. I went as far as takin the dashboard out and there it was.
Can't say whether it was pinched or not. But by then, I had the issue all figured out. Again, using the technique I described above. Thanks for you input.

 

I had mine do this at a gas station and had to get a guy's pliers to unscrew it. Even after that, I had to use both hands to turn it.

My solution...Wille G cap. With the shape of it, there's more to grab onto and I can turn it with one hand with no problem. Plus I like the looks of the cap.

 

There you go busting my bubble again. I thought it was just my 16" arms but now you tell me it's my cap.

 

This happened to the Heritage demo bike at the dealers. I saw him trying to unscrew it and he couldn't.
It then went into the workshop and they couldn't get it off either, because when I took it out the fuel light was on and I was told "don't go too far it's nearly empty!"