Carburettor service kits and rebuild kits provide the replacement components needed for routine maintenance and comprehensive overhaul of the SU carburettors. The kits are specific to the carburettor tag number, and this number must be quoted when ordering to ensure the correct needle, jet, and gasket specifications are supplied.
Gasket Sets
Service kits contain the most frequently replaced items: the needle and seat (float valve), float, gasket set, and jet. These are the components that wear or deteriorate during normal use and are the items renewed during a routine carburettor service. A service kit addresses the most common causes of poor running, a worn needle and seat allows the float chamber to overfill (causing flooding and rich running), while a worn jet or incorrect needle produces a mixture that is either too lean (hesitation, popping on the overrun) or too rich (black smoke, sooty plugs).
Rebuild Kit Contents
Rebuild kits are more comprehensive, containing everything in the service kit plus additional items such as the throttle spindle and bushes, throttle disc, choke linkage components, and all O-rings and seals. A rebuild kit is appropriate when the carburettor has been in service for many years without overhaul, or when the throttle spindles have developed excessive wear that allows air to leak past the spindle shaft into the carburettor bore, causing an air leak that makes mixture adjustment impossible.