I had to replace my fuel line (from petcock to carbs). I searched BA and found many people offered the same advise, take your old hose into the parts store to size up. I did that and I still ended up buying a few different sizes.
To save members some time, if they have a 1G 12B like mine (and possibly other bandit flavors too), they can get excellent fitting fuel line hoses from Oh Oh Oh O'Reillys called "XL FUEL LINE 5/16 INCH (8.0 mm) SAE 30R7" made by Gates. That should be enough info to get exactly what is needed from them.
Hope this helps someone.
Edit: This thread will be moved into the FAQ in a few days, so if you know of other good lines, add it to this thread before it moves and becomes read-only. - BA StaffJesse