It's way too small to be for the fuel inlet. The larger black ring to the right of it is for that.

Where is the "Idle compensator" in the diagrams? The Factory Service Manual mentions it, refers to fig.5 but must be some sort of misprint because it's not in the fig.5 it refers to and I can't find it in any other diagrams in the FSM. Is it in the exploded parts view? Does anyone know where on the carb it is located? Thanks