Using the Uni-Syn is the fastest and easiest way to synchronize airflow through twin carbs. It is much more accurate than putting a hose in your ear. (Though not as much fun!) A must-have for anyone maintaining twin carbs!
This subject is a regular message-board poser. Many of us have touted our preferences and discoveries whilst playing about over the years. One problem with trying to deal with it on the message board is the sheer volume of information offered and available against the time available to post it.
Being an oft-voiced question on the message board, I thought I'd share it with you. Since there is already a very good source of starting points/applications for fixed needle carbs, this is for those floundering about in the wilderness that is the biased (swinging) needle example of the breed.
Before proceeding to synchronize your carburetors and for best results, some preparation is in order. Your carburetors should be in peak condition with no play in the throttle shaft bushings. If these bushings are worn, synchronization is difficult or impossible to achieve since there will be a vacuum leak past the bushings. Additionally, the jet needles should be identical and correct for the application; adjusted to equal and correct seating in the piston and centered in their jet bores (if not centered, you will feel a bind when moving the piston up and down).