Old Fuel in a MC tank

[BobL]

My bro picket a 1980's BMW for $300.

He reckons it had been sitting stationary for at least 10 years and the remaining fuel in the tanks smells like turps.
It has also turned some of the rubber parts inside the tank (not the hoses) into black goo and would like to know if it is decomposed fuel or turps or something else has been accidentally put in the tank

He has a vid about it on his Youtube channel (FangitJoe) https://youtu.be/lO57w_a3Pq0 skip to about 9:30 if you just want to look at the goo.

Thanks

[Ray-s]

Bob, I would say just decomposed fuel. Modern fuel does not store well and way worse if it has any ethanol - something I found out about the hard way.
I had a fuel pump assembly in one of my Buells completely toasted after sitting for for 3 years.

The fuel smelt really bad and had formed a layer of black sludge towards the bottom nicely covering the fuel pump assembly - here is what looked like it came off the Titanic.

382711

One interesting side effect was that all of the wiring had the exposed copper wiring dissolved well into the wires with just the plastic outer remaining.