I drained my gas tank so I could rebuild the petcock. Anything I should do to the tank while it's off the bike and empty?

Might Want to line the inside.

How do you line the inside?

Yes, please elaborate.

pour a bit of two-stroke oil in there and tip it on all sides. coats to prevent rust.

It depends on how bad your tank is , and what you want to do.
A perfect tank should be oiled and kept indoors.
A lightly rusty tank can be chemically or electrically cleaned.
A nasty tank needs drywall screws, lengths of chain, or gravel and lots of shaking and rinsing, then maybe- -
Further prep for a coating, or,
Dried and oiled because you're gonna run a rusty tank with a paper filter.

Then there's sending it to the radiator shop for a Pro boil-out.

Gadfrey, no gravel! NO GRAVEL. Tried that. Bad idea; had one h-e-double hockeysticks of a time getting it back OUT.

For a slightly rusted (no real rust-through or even surface deterioration) tank, a flush with phosphoric acid seems to work the best, at least I've used it twice now with good result.

It's sold as "concrete cleaner" at Lowes or Home Depot (but read the label, some AREN'T phosphoric acid.) Dump the whole bottle in the tank, add water, shake, and let sit for an hour or two or three.

Immediately after flushing it all out with clean water, flush with SeaFoam, gasoline, kerosine, or a mixture. I used Seafoam/motor oil/gas mixed. Then a shot of SeaFoam in the first tank of gas, and all better since.

Inline fuel filter of course, the in-tank filter only stops boulders.

Get gravel out of your tank by using a shop vac and a smaller hose.
You have to use the right size gravel, of course.

And don't shop vac anything with Gasoline fumes.
Clear fumes by running car exhaust into a tank for a few minutes.

please don't put that liner stuff in the tank unless your sure it needs it
myself i'd rather see rust than liner, at least i know what i'am getting

Polock,

Why no liner? Are there issues with using the liners?

TIMEtoRIDE wrote:

Get gravel out of your tank by using a shop vac and a smaller hose. You have to use the right size gravel, of course...

Sounded good in theory. I used aquarium gravel. The hose I rigged up for my shop vac was small enough to get into the "corners" of the tank, and worked reasonbly well for about 97% of the gravel, except for clogging up periodically. It was that last 3% that really did NOT want to be removed, and had to be chased down one granule at a time. The whole experience was frustrating as all get out, and didn't work that well, despite shaking the living bejabbers out of the tank for quite a while.

That's when I decided to try the phosphoric acid, and it worked quite well.

On the subject of liners, I tend to agree with Polock. Heard about (and seen) too many failed/troubled lining jobs to make the gamble worth it. Yes, a lot of people have used lining products with great success but I would consider it a last-ditch effort, not a sound preventive measure.

some guys use liner and say they follow the instructions to the letter and the liner works perfectly for a long time
then again
some guys say they follow instructions to the letter and after a short
time the liner starts pealing off and makes a real mess
then you start cleaning it out with MEK and have a real mess on your hands

So moral of the story is.... Use phosphoric acid or gamble that things will get messy between the gravel or liners.

Just let the tank dry and wash the inside with acid. Let dry then fill with gas. Did I get that correct?

Add a couple steps- -
Rinse with baking soda/water to neutralize the acid
flush out with denatured alcohol to quickly grab up the remaining water
Oil it immediately, even with alcohol

And for anyone doing the coating, the few pieces of gravel or stuck drywall screws get embedded and coated into the liner.
obviously don't oil if you are lining it.

TIME is right, you need to oil or similarly coat the inside of the tank immediately after the acid treatment to prevent flash rusting.