The first step is to get the throttle slides both opening at the same time. This is easy when the carbs are off the bike and I always check this when I have them off. It’s a bit harder on the bike especially with splayed heads. The way I do it is wind the throttle stop screws right out so the slides don’t rest on them. Then place a 3/8” drill bit (metric equivalent will do here if you’re not a purist) underneath each throttle slide. Now adjust the throttle cables so that both drill bits drop at the same time and there is a little bit of play at the twist grip. Now wind the throttle stops to get the bike idling. Make sure you do this with the bike warmed up. The next adjustment is the air screw which the manuals tell you to adjust until the fastest idle is achieved but to be honest I don’t bother with this, I just wind the screw out to the factory setting and leave it at that. The air screw only affects the carb at 1/8th throttle so as long as the bike takes of okay from rest it is okay. (Anyone have a different view on this?)