Re: Yet another mixture thread, or...? (Starting problems)
Turning the fuel valve to the off position is like an 'insurance policy'. If the float, needle, and seat function as they should, your carb won't know the difference between 'off' and 'on' when the engine isn't running. If you do have a slight/major problem, you won't flood your engine with fuel mix. You won't run fuel mix onto your garage floor. You won't possibly explode your house when those fumes reach the hot water tank's pilot light.
Pretty cheap for an 'insurance policy'!!
You're never lost until you run outa gas.