It is well worth familiarising yourself with the way an Amal carb operates...Until you grasp the principles there is little chance of correctly diagnosing faults and making the right adjustments...
In the 'Technical Section' of the website look up the 'AMAL pdf.' posted by Steve Madden....Alternatively look on the internet or aquire a copy of the BSA M20/M21 factory worksheets which contain a section on carburettors (as well as a lot of other essential information).....These are available in reprint but there are still originals around...Ian