Removal of OEM tank liner

[Seth]

Any suggestions for removing the OEM BMW liner from an R90S?
Only small strips on the bottom are soft and pealing. The rest is intact.
Most products, Red-Kote and POR would prefer a bare, dry metal surface to work with.
My prior experience is with POR and tanks that were bare metal to begin with ('71 BSA, '72 Yamaha, 73 Triumph).
Their cleaner followed by metal prep worked well, but I'm not sure the cleaner will remove the BMW liner.
Thanks.

[melville]

Vinegar. Ordinary vinegar will remove it, and leave a nice metal surface to work with.

I think it was $2/gal, so I had no problem buying 6 gallons and letting it soak for a weekend.

[hal]

Cool, do you remember how many % vinegar that was?

[melville]

Cool, do you remember how many % vinegar that was?

Whatever they sell in the salad dressing aisle at the grocery. A quick walk to the kitchen shows it to be 5% Distilled White Vinegar.

[montmil]

Some folks on the R65 forum have been using plain white vinegar with good results in removing scale and old tank liner material.

One member added a cup of salt to 5.5 gallons of 10% plain white vinegar. The salt reacts with the acetic acid in the vinegar to create sodium acetate and a mild hydrocloric acid. After several days soaking, the tank was drained and flushed with water and baking soda to neutralize the acid. Shiny bare metal resulted. A word of caution... do not totally seal the tank during the vinegar soak. There is a gas pressure build up that is strong enough to shoot a rubber plug out of the petcock and shatter an overhead fluorescent shop light. YMMV