I took my gas cap off to...

[beemuker]

I took my gas cap off to have a look see, and the gasket has a cork/powder-like substance on both sides. was that some kind of cork or sealant that has deteriorated. ? the rubber gasket looks fine and the metal tank surface does not look corroded, just this residue on it. I guess I should order a new gasket and maybe some other small parts [tranny crush washer, fork cover cap] best online source? I would think the new gasket would require no sealant. tips?

[Tuco]

I dont recognize whatever that stuff is/was. However in your third photo, it appears that you still have the unleaded fuel nozzle restrictor still attached. Remove it and you find the tank easier to fill and a bit more capacity.

[beemuker]

thanks, i was wondering if I could get rid of it.

[thegingerbeardman]

I have had 2 K bikes with the same residue.  Both sat for at least a few years.

as the parts fiches don't show anything else that should be there i.must conclude it is some kind of corrosion or residue leftover from gas that has sat for Way Tooooo LONG

clean it off, I replaced the rubber thing too as mine were fairly hard, and keep on riding

[vintagemilano]

It's corrosion, when aluminum corrodes the resulting powder is a different color than when ferrous metals corrode.

[beemuker]

It's corrosion, when aluminum corrodes the resulting powder is a different color than when ferrous metals corrode.

I guess I need to clean it off without getting it into the tank. might be easier with the tank off. I could wait until I need to do an air cleaner and coolant flush this winter. It's probably been that way for awhile. do I need to do this asap. ? should I put some kind of oxidation inhibitor to prevent this in the future?

[herseyb]

I had the same stuff on my bike that sat for god knows...

I did clean it when I had the tank off, plugged the whole beneath to make sure none of it got in the tank.  Wound up replacing the rubber gasket too.   The tank didn't stop going ffffffffsssssssssssssssssss  under pressure until I also replaced the rubber.