I was reading the mopedwiki article on the aforementioned subject and it listed using vinegar as a tool for removing rust. I have a few questions before I relate to you my great epiphany.
Has anyone tried this?
How well does it work?
Okay, so assuming that the answers to both of the above questions are at least "kinda, sorta," I have an idea that might turn "kinda, sorta" into "a little bit better than 'kinda, sorta'"
Lately I've been rebuilding my darkroom, and one of the chemicals used in photographic development is this solution called "stop bath." Stop bath, when mixed to be used for photographic processes, is acetic acid diluted to 28% in water. Now, distilled vinegar is nothing but acetic acid diluted to 7-ish% in water. But there's more, when you buy stop bath at photographic supply stores, it comes in a highly concentrated form, probably >90% acetic acid that you're expected to dilute yourself, so you could buy a bottle of stop bath for about $5, and dilute it to say 50% concentration in a gallon of water, and this could, hypothetically, be much more effective than vinegar, which is only 7%.
Unfortunately, (or really, rather fortunately) I don't have any rusty tanks on which to test my hypothesis, but if anyone wanted to try this, I would be really interested in seeing how it works out.