Dave,


The low-speed needle affect fuel flow, even when it is completely out of the nozzle.

Since fuel is a liquid, its flow will be reduced even if the needle is 0.5-1 mm out from the nozzle, because its presence there will force the outgoing fuel to alter its route.
It is true, however, that its major influence is when its tapered tip interacts with the nozzle, effectively changing the size of the fuel orifice.
I.e.; increasing it, as the throttle opens and it moves progressively out of the nozzle; and decreasing it, as the throttle closes and it moves progressively into the nozzle.


As to your 'back-tracking'... i.e.; ' the 'idle range' is any carburettor setting, in which the low-speed needle's tapered tip affects the fuel flow...
It is akin to statements like; 'wherever I lay my hat, that's my home'...


This is the part-throttle range and using the term 'idle range' to describe it is wrong and misleading.