So while the 51 is at the machine shop we got the 49 6v pulled over to the shop, got the hood off and repaced the dizzy cover as it was broken, cleaned and set the points, new spark plugs as it had gapless plugs for some reason, checked oil and coolant (which will be changed) rigged up a gas tank from a lawnmower and she fired right up and sounded great. Now this tractor had been sitting for 15 years, thank god no rebuild on this one. So here is my question, i took the gas tank off cause i knew it was dirty inside, Had probably half a gallon of gas (varnish) inside. Bottom has varnish but the sides have a light coating of rust, how do i clean it? I already took the bowl assembly off to be replaced. I don't plan on lining the tank after cleaning, just clean her up, rewire, tap out some dents and throw a for sale sign on it! Would toilet bowl cleaner work? Thanks!!