I'm working on a string trimmer currently whose adjustment screws are not labeled - or the labels have worn off with time. :) For reference, the carb is a Zama. It seems to me that there is a standard protocol on which adjustment screw is which on diaphragm carburettors.
From my memory, the
L screw (low-speed jet) is closer to the engine block, and the
H screw is usually closer to the air filter. Can anyone confirm or debunk this?