Alright guys,
                   an old biker here. Use dish soap, water and gravel (BBs,
steel shot for shotgun shells, glass beads for sandblaster, etc.) to get the
loose rust out.  Then go to Home Depot and get a bottle of perchloric acid
or muriatic acid.  Drain the tank, rinse well and add a small quantity of
the acid.  DO NOT breathe the fumes, they are dangerous!  Put an old gas cap
on and slosh the acid around the tank so that the inside is coated with the
acid.  Let it set for 30 minutes. Rinse and repeat until the metal inside is
free of rust (water will dilute whatever acid is not neutralized to the
point where it is safe. This is exactly what the directions on the kit will
tell you to do).  Now is the time to use the two-part sealer.  You can buy
this at most motorcycle shops, some auto parts stores or at www.eastwood.com
and type in keyword "gas tank sealer".  I use the stuff from Eastwood, it
just seems to do a better job.  Follow the directions.  You do not need the
entire kit, save yourself some money, the cleaner in the kit is perchloric
acid and it is cheaper at Home Depot.  I have a Harley that I treated in
this manner twelve years ago, it is ridden daily, and I have yet to have a
problem with it.  Fuel filters are always a good idea (but I have had the
same one for eight years and there is still not any rust in it).

Later,

Moon