What Ron said... once you're sure about the ignition and the valves, and you're sure there are no vacuum leaks, go through the carbs in this order:

1) Be sure the pistons in the carbs are free to drop all the way down on their own. If not you need to center the jets on the needles.

2) Use a meter, or listen at the carb intakes through a piece of hose, to make sure they draw the same amount of air at idle. Balance them with the two idle speed screws so they read/sound exactly the same.

3) Look at the pistons as you work the throttle by hand. Both should lift from their idle position at the same instant. If not you need to adjust the cranks on the intermediate linkage so they do.

4) Adjust the height of the jets evenly on both carbs for smoothest/fastest idle, counting flats. Once you have that, try varying one carb up and down one flat and see if that improves it further. Try the other carb separately. If you have to fine tune more than one flat, something else is wrong.

5) Reset the idle speed and recheck the balance. Do steps 3,4 and 5 over until it's all perfect.

6) Do not install the air cleaners upside down or they'll block the air holes to the domes.