The factory settings of the engine are as following and are a good starting point for you. Turn in the needles completely (Caution: Do not
over tighten them!) and loosen them the required number of turns:

Idle screw: Should be open 0.5-1.0mm.

Low speed needle: Should be open: 6,75 turns

High speed needle:Should be open 5,00 turns

CARBURATING PICCO ENGINES
Engine works better on the rich side (HSN) and normally needs more than a couple of laps to reach the operational temp. Start on the rich side (HSN) and after 4 or 5 laps tune the engine. Doing this process on the bench (or starter box) normally overheats the engine driving you to a wrong tuning and maybe causing a damage. Set the engine a little bit rich (if you progressively open the carb, the engine responds quick but at 3/4 rpm becomes rich (not really 4 stroking but rich) Then at the track after several laps (at least 5) if the engine is still rich lean it.

Regarding LSN, Run the LSN a little bit on the rich side and still keeping the engine with a good idle (Very low rpm idle, is better for fuel consumption and handling of the car after off throttle).
After pre-heating the engine, just pinch the fuel line and if the rpm remains the same for 4 to 5 seconds and then the engine revs up and shuts off, that’s the best setting for a large track with long straight away. If the track is really short, and full of hairpins, LSN needs to be more lean, because the engine never revs up for a lot of time, and so if you keep the same setup described before it is always rich out of the corner.

AFM