Best idle mix setting for 32/34 on 1.3

Ok I don't have one of those guages for setting the idle mix - I have just got the idle speed as in the carb manual and set the mixture so it idles at 1000rpm (as even with choke its groggy when first started till it warms up)

For max performance - Should I back off the idle mix screw as much as possible without it sounding rough?

Apart from getting carbon on the plugs and not being too good for the engine what would opening the idle mix screw (delivering more more fuel) by say 1.5 turns more, do? - More performance at higher revs? - I can't remember.