VHBZ carburettors

I am struggling to set the carbs on my V50 II and although I have got them well matched on the vacuum guages the pilot screws don’t seem to make much difference to the way the engine runs on the bench although I can notice a difference with different settings when riding.
Therefore my question is:

Does the pilot screw on the VHBZ carburettor control the flow of air or fuel ?
In other words does turning the screw clockwise decrease the fuel flow or the air flow ?

Which side of the slide is it? I think it controls fuel if on the engine side, and air if on the inlet side.

They control fuel, wind them out to richen it and wind them in to lean it off. Remember these only work on the idle circuit so therefore only work on low throttle openings.
The pilot screws are to the front and the tickover adjustor is the larger one further back.

Not sure if you have seen this.
https://www.thisoldtractor.com/dellorto.html
Hopefully helpful
Steve.