SYN002 Synchrometer Weber Jets / Chokes & Components Carburettor Synchrometer (BK) These are for synchronizing all multi-barrel or multi-carburetor automotive applications. This handy device measures the exact amount of air flowing through the carburetor, making the idle speed and mixture adjustments much more precise. The BK Synchrometer has a larger airhorn adapter and is designed to flow more air than the STE SK. It works unaided in airhorns from 2\' (51mm) to 2 5/8\' (67mm) in diameter. The STE BK measures flow mass from 1-35 Kg/Hour