Re: Some may want to know-46 g. tank info
I lost my patience with spending 10 minutes squeazing the last 6 gallons into my 46 gal tank a couple of years ago, so duplicated Eric Badger's modification. It's a real PIA to drop the tank, but it allowed me to insinuate an air powered die grinder and enough of my arm through the filler neck port.
The vent is surrounded by a piece of approximately 2" pipe a couple of inches long welded to the top of the tank forming a collar that creates a large air pocket at the top of the tank that necessitates the excruciating process of using full tank capacity.
After getting the tank out an siphoning out remaining fuel, I used a ball tip carbide bit on the grinder and ground a vent hole in the collar around the vent opening. I "vacuumed" the metal filings from the tank with a magnet, and left a couple of magnets stuck to the bottom of the tank to catch any that I missed.
The last 6 gallons now go in as fast as the first, except for the last gallon to fill the filler neck, and there have been no problems with intakefilter clogging with filings, when I dropped the tank (again) last year after several thousand miles. I removed the magnets, cleaned off the few accumulated filings, and replaced them in the tank.
It was a lot of work, but ultimately worth it.