[Gaz64]

Hi Paul,
If where your mixture screws are now make the engine run correctly, not rich or lean, at an A/F ratio of around mid 13s, (technically 14.7 would be nice), then turning them out further will only richen the engine at idle.

2 turns out, says the idle jets are too lean.

The idle jet is really the low speed jet, carries the engine up from idle as the transition circuit, to overlap with the start of the main circuit.

The mixture screw can be used to analyse the transition circuit.

For example, we wind the speed screw up to 1400 rpm or so, we note the engine behaviour, (gas analyser preferably), then nudge the mixture screws to add or remove so fuel accordingly.

If we need to open them, then the idle jet is too small, eg: step up from 50 to 55.

And then vice versa, if you need to close them.

Gary