Fixed airjet mod

Drill a +/- 2mm hole inside the middle brass boll

Turn a screw inside the boll

Use a side cutter and pull the brass boll out (use some liverish on the side of the carb)

Gently wiggle the last mm out

Drill the hole the same diameter as the brass boll, about 10mm deep (just past the original air intake of the airjetlets)

Then tap M4 into the remaining part, and fit the airjet

A closer look with what I mean with drill past the original airjet intake

Plug off the original airjet intake with a rubber hose, or bold, or whatever