Cleaning out tank

[Guest]

I am slowly working on my 1982 GS750E. Steve cleaned my carbs for me (thank you very much for your excellent work) and I checked and set the valves. My carbs were gunked up pretty bad and so I am wondering about the inside of the tank. If this were your bike, what would you do with the tank and petcock besides dump out old gas?

[81GS850]

Use phosphoric acid to clean out any rust in the tank. Then either red-kote tank liner or leave it bare and never put ethanol in the tank. I would try an inline fuel filter unless you get funky running issues with the bike.

[winfield]

Sorry, I was not clear as to the problem. There is no rust. I am wondering about the gas having turned to gum like it did in the carbs. Would there be some of that in the bottom of the tank around the petcock and would that either block the petcock or get into the small passageways in the jets that were just cleaned?

Should I clean out the tank with something to get out the gas-turned-to-varnish (if there is any) or should I just open up the petcock and see if the flow is fine and if so, just put new gas in and forget about it?

[Chuck78]

Good idea to flush the tank with a paint safe degreaser & flush again with a little gas after sealed & sloshed around. Make a steel blank off plate for the petcock hole, you need to pull it anyway to inspect the bottom corner of the tank for general condition.

My buddy had no petcock problems, but took it apart anyways to clean the gunk out if it. Put it back on and it leaked ever since, ended up replacing it. The gunk had been helping keep it sealed up apparently.

I pulled a petcock out of a tank that I flushed 3 times with 1/4 gallon gas (came out gold tinted every time), pulled the petcock, & found some crud around the inlet filter screen of the petcock. Its got a pretty fine mesh screen to keep debris out, but that doesn't prevent the gas from sitting & turning to varnished gum.