The purpose of carburetor synchronization is to adjust all the carburetors so they have the same air flow through all of the carburetors. If the carburetors are out of synchronization, they will receive different amounts of fuel and air. Carburetor synchronization means adjusting all of the slides or butterflies to the same height at all times.
Most motorcycles have one carburetor that has no adjustment while the others can be adjusted.
The non adjustable carburetor is used as a point where all others are adjusted too. You must decide what type of adjustment set-up you have. There are two types of vacuum gauges that most types of mechanics use. One type uses four individual dial gauges, fig 1 while the other uses mercury in a set of glass tubes, fig 2 . Most motorcyclist will find the mercury gauges will work good considering their low price and ease of use.