Scooterotica

S2 Li, TV175 barrel, 150 gearbox, SH1/20 carb jetted as s3 TV175 (5914-1 slide, 5899-2 atomiser, 106 main jet, 50 choke, 50 pilot jet) Casa s2 clubman.

Kicks over, sounds like a machine gun on idle with tickover really high. Revs clean but then settles down to super fast tickover. Stalls when choke put on.

Would it be the mixture screw and pilot jet I need to work on?

Quite possibly.
But first, you haven't got the throttle cable too tight have you?
If that's good then are you sure there's no air leak?
If not, the pilot is potentially too small, giving a too lean air/fuel mix. Having said that, you say a 50 pilot is in place! This is unusually large !!
The mixture screw only becomes effective when the pilot jet is correct and gives only minor adjustment.

Throttle cable loose. I’ll check air leaks.

Would you say it’s a symptom of too much air rather than too much fuel?

Usually too much air.