Assuming they haven't been messed with, nothing. Sync the carbs first before you start messing with the pilot screws.
Did you rebuild the carbs? Float levels all set the same? Diaphragms good/not leaking?
I've never done the 650 carbs. I would guess pilot screws should be between 1.5 and 2 turns out from the factory. This link's got a manual for the 80' CB650...procedure should be similar:
Since I'm on fucking turtle-net and don't feel like waiting an hour to load the whole manual...hopefully it's in there!
And, since the damn thing is showing up in the post as a fucking U tube or something...here's the address for a copy/paste (Remove spaces) www.scribd.com/
doc/ 50487631/ Honda-CB650-1980-Service-Manual
FML - I feel like an old person who can't use the internet