The current E5 unleaded fuel is to be replaced with E10 which has a higher biofuel ethanol content. Anyone know if this will be a problem for 1980s smallblocks?
If it has a plastic fuel tank, then I imagine it will be more disastrous more quickly than the E5.
Otherwise I think you will need to check all plastic components that occur in the fuel line from tank to carburettor/injector to see if they have been designed for ethanol compatibility.
My V50 will only run happily on high octane anyway, and that has been more likely have not contained E5. Only problems I’ve seen at that level is the short life of the fuel lines.
Biggest problem is more likely to be when the bike is left standing - ethanol being quite hydroscopic I believe.
Just to mention, I was changing fuel hoses fairly often back in the days of 4-star.