http://www.common-motor.com/
This video shows the two step process on how to preform the proper carburetor synchronization on the Honda CB350, CB450 and CB500T family of motorcycles. Step one - setting the idle speed synchronization, aka "bench sync." Step two - adjusting the progressive synchronization, which means having the carburetors open and close at the same rate when the throttle is twisted.
New throttle cables and a throttle sleeve ensure smooth and proper synchronization.
CL / CB350 Throttle Cable: http://www.common-motor.com/honda-cb-cl-sl-350-throttle-cables
CL / CB450 / CB500T Throttle Cable: http://www.common-motor.com/honda-450-throttle-cable
Nylon Throttle Sleeve: http://www.common-motor.com/honda-throttle-sleeve