As per 109e's comments.... The idle stop screws are the first and simplest place to start while synching and fine tuning the carbs. I have had high and hanging idle before when everything was in good shape but the idle stops were set just a fraction too high. More than once. (I try to keep my idle at about 1000 rpm for better cam oiling at idle.) +1 on at least a 10 mile warmup - more if you are in cold temps.