i have a 3/4 clutch slave cylinder, what size master do i need to use?

 

You would need to know the stroke, of the slave cylinder before you can size it perfectly, so to be sure you can push enough fluid, but as a rule if you use the same stroke/movement at the pedal then you're obviously going to get the same range of motion at the salve end, if in doubt go slightly larger at pedal end, ie next size up, or alter pedal pivot point for more/less stroke as needed.
Stroke of slave normally around 35-40mm.
tabetha

 

wots it going on