carb drain question

[Dustydes]

Petrol is NOT hydroscopic. Hydroscopic things absorb water. Petrol floats on water which is why some petrol tanks have rust holes in the lowest points.

Depending how long you plan to store it decides the plan of action.

If only a few months, fill the tank to the brim to stop any moisture getting in through the breather tubes etc and just leave it in the garage unti you want to fire it up. The battery will need to be maintained.
If it is for more than a few months, then yes, drain down the tank and coat the inside or fill it to the brim and be prepared to drain it before you want to use it again. The float bowls should be emptied too to stop any varnishing in the bowls.

Google Hydroscopic

Fuel will attract water molecules out of the air which will not mix but settle at the bottom of a tank mixing with oxygen to create rust.
Short term no harm but long term, rust

Water sinks in petrol which is why petrol floats on water.