Replace MA18BS5 with PHBL 25 Jets for Li125 ?

[AndyVee]

Due to constant problems with my original MA18BS5 I'm going to replace with a PHBL 25. My question is what would be a good start for jets to start the tuning process ? There is a good guide at Cam Lam but it only really aligns the PHBL to upgrade kits not really to stock engines. (Engine is standard Li125 S 2 but with clubman exhaust)

Link bellow, any help welcomed,

www.lambretta.co.uk/downloads/carbjetting.html

[Scooterslag]

Think the 25mm might be a bit too big for a standard 125 engine, would probably use either a SH1/18 or SH1/20 Dellorto, you could probably pick up the SH1/18 for pretty cheap coin. paul