I'm finally restoring my 1987 K75S after being stored for nearly 30 years. The tank was completely drained and removed (along with all the tupperware) before putting the bike away but now I noticed the inside has a brownish-copper hue instead of a natural aluminum color. Is this normal or will I need to clean whatever this is out?
Thanks for any advice.

Mine has the same residue - no problem, but it will be interesting to hear of a solution to get it cleaned.

I Left E10 petrol in my K1100LT tank and it went off (don't ask). The result was all the rubber turned to mush. When I emptied it I had a similar residue but also lots of rubber mush to clean out. I Also needed to buy all new internals, but yours look o.k. The residue inside yours doesn't look too bad.

I removed all the internals, fuel cap and mounting ring then used white vinegar and different sized brushes to clean the tank out. A thorough rinsing using a hose pipe seems to have cleared everything, but getting the last dregs of water out took a while. 

It is like new inside now, ready for the new internals to be fitted (but my garage is too bloody cold at the moment!). 

I'll post a photo when I get back home.

Mike

mike d wrote:I Left E10 petrol in my K1100LT tank and it went off (don't ask). The result was all the rubber turned to mush. When I emptied it I had a similar residue but also lots of rubber mush to clean out. I Also needed to buy all new internals, but yours look o.k. The residue inside yours doesn't look too bad.

Oh I know all about ethanol fuel going bad, it doesn't take long!

My internals were shot as well, the pump was long gone and all the rubber turned rock hard. That's all new stuff in the picture.

I let a half tank of E10 sit in my 93 LT for almost 8 years. No issues. Tank interior and fuel pump vibration ring were fine. But I have a dehumidifier in my garage that keeps the relative humidity at 55 or less so there's less water in the atmosphere for the E10 to absorb.

duck wrote:I let a half tank of E10 sit in my 93 LT for almost 8 years. No issues. Tank interior and fuel pump vibration ring were fine. But I have a dehumidifier in my garage that keeps the relative humidity at 55 or less so there's less water in the atmosphere for the E10 to absorb.

I live in the tropics, air you can wear if you know what I mean. There is a station not far from me that sells ethanol-free fuel, although at quite a price premium. I fill several five gallon jugs with it at the start of every hurricane season to feed the generator (just in case) and lawn mower. At the end of the summer I'll use what's left (no major storms here so far, knock on wood) a few gallons at a time in the cars. I've actually kept it for over a year, no stabilizers, and it seemed to still work fine.
The only caveat, besides the price, is that it isn't considered a top-tier fuel. I always thought that was just marketing wank but apparently there is an actual difference, primarily in the additive package. I'll stick with the good stuff.