zx7r overflow gas leak from bottom of tank?

Answer 1

Could be the gas cap isn't making a good seal.
When you see it leaking, sniff around the gas cap.
One of the overflow tubes, lead right up to the gas tank filler hole.
If there is any spillage during fill-up, the excess fuel will drain down the hole (open the cap and look at the hole - all sportbikes have them).