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What is in my gas tank?

Jdlong27

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Just as the title says. At first I thought it was all rust. Seeing as I had gas seeping out the bottom of both bottom "lips" from what turned out to be pinholes when I stripped it to metal. So, I let the tank soak in Metal Rescue a few days rotating as I went. The MR came out looking okay with a few loose grains of something, but it wasn't black as I had expected. And the tank looked the same inside.

So does anyone have any ideas? I'm not sure if it's rust, crystalline gas (varnish), an old liner, or a combination. My next thought is to soak it in acetone for a few days and see what happens, but would appreciate any input.

Still can't add pics from my phone, so here's a link to the pics of the inside.

https://www.dropbox.com/sh/5d3c5njyotjw56x/AAA5PTXONb_nAblLHpS42uE-a?dl=0

Thanks in advance!
 
Just an update. I put a gal of acetone in and sloshed it around for about four hours. It stripped most of the old junk out. I then took it to the car wash and pressure sprayed it with soap and then rinsed. Brought it home and filled it with oxy clean and water and let it sit several hours. Today I've added three 1' lengths of chain and a qt. of MEK. Been sloshing that and will over the next several days. More to come.
 
No more to come. Lol I messed with this thing for weeks. Pressure washers. MEK, acetone, chains, etc. apparently I had a failed liner in the tank, along with major dents and rust. Went looking for a different tank and ended up with a different bike! Haha. Bought an 80 cb750f frame and two tanks for it. Just didn't want to leave this hanging.
 
You have gas tanks "Boiled out" at a machine shop or possibly a radiator shop. This will also remove most of the paint on the outside too.
 
I tried that. I must live in a bad place. Four radiator shops all referred me to a fifth. I called the fifth and he won't touch a tank with a previous liner. Said he's had too many he couldn't get all the way out with his processes and even MEK, which he suggested I try again.
 
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