If you are riding a street bike, it probably has two or four cylinders fed fuel by 2 or 4 carbs. Typically, each carb feeds fuel to a one cylinder at a ratio of either 50/50 or 25/25/25/25. If any of the carburetors are feeding their respective cylinder a higher or lower amount of fuel/air mixture, the cylinders are producing different amounts of power which will cause poor engine performance. Synchronizing the carbs ensures that each cylinder is receiving the same mixture as the other, and thus all cylinders are doing their equal share of the work. An out of synch carb can produce engine knocking, poor idle, fluctuating idle, reduced power, backfiring, etc. If your bike is exhibiting any of these symptoms, it is probably a good idea to get it to us for an adjustment.
Carburetor synchronization at GMW typically runs $160 plus time required to access the carbs.