I tend to run the carbs dry when storing.
I only use super unleaded fuel (High Octane 98 low ethanol content) with added Miller ethanol killer.
Use this in the more modern stuff also as I have seen some horror stuff on some friends machines, fuel lines turning to black gunge internally which were supposedly ethanol resistant.
If I store a bike with fuel in the tank, tank full with pure super unleaded 98 octane or Av gas if I have any floating about.
We are still E10 fuel free more or less in N Ireland our neighbours in Scotland are more and more on the E10.
Caution I had AVgas in my Comet last winter came into the garage very late one night to fetch a torch and thought that's a strange smell.
Floor covered in AVgas by the time I cleaned it up was as high as a kite,bonus!
That's when I decided to wear brightly coloured clothes and change from Ewart taps to modern stainless ball valve taps.
I like to clean my carb bits in the ultrasonic with 10 to 1 carb cleaner solution the only way to prevent fuel separation and the consequences is not to use ethanol fuels drain, dry and clean away the residual fuel.