Which fuel valve? The petcock or the the valve inside the carb? I just chucked the stock petcock. I have never noticed a black vitron tip on the float needle, but maybe I never looked close enough. When I drill out the jet I'll probably take a better look then. I'm assuming the float needle is the same thing as the slide needle, or is this something different?
EDIT: I am guessing this is what you're talking about?
I haven't looked at the actual one in my carb, but this one does not appear to have any special tip. I could be wrong, but it appears to be bare metal. If mine does have a vitrol tip, is there any way to modify it so there are no issues with the ethanol?
I soaked the float for a while in the ethanol and it didn't seem to make a difference. Other things I soaked in it like a tupper ware container got screwed up and a plastic cup I had melted pretty quickly, so I guess that's a sign that either the float won't corrode or it will just corrode over a long time.
Is it more likely that the seals will get wrecked over a longer period of time? The seal on the float bowl was the only one that melted pretty instantly. I took off the clutch cover gasket and soaked it for several minutes in the ethanol and nothing happened.
The only seals that haven't been replaced is the main engine gasket and the gasket between the engine and the cylinder. The intake, exhaust, float bowl, clutch cover, and magneto cover gaskets have all been replaced with better material that seems to withstand the ethanol.