try this , drain the tank , scrub the tank with soft scrub with bleach,rinse well and dry, wipe down with acetone, let the tank set like this for a week with the cap off, scrub ,rinse,dry and wipe again right before you put on the new graphics, let the graphics set on the bike for a week before you fill it up. and probably most important is to drain the gas out of the tank after each ride and leave the cap off . lay a rag over thegas tank opening loosley so no dust can collect in thetank but the gas fumes can escape easily.
since I finally broke down and bought graphics for my bike this is going to be my plan of attack. remind me after awhile and I will let you know how they hold up.