I used phosporic acid and chains on the drill chuck. My tank was roached on the inside, several pinhole leaks. I used KBS Gold Standard tank sealer. Really good stuff, it came out perfect. Do not get the sealer on anything you care about, only time takes it off. There are before and after pics on my 1981 KZ550 Update thread. R
1980 KZ 1000E2
Crashed 6/2016
1980 KZ550A
Sold 3/2016