A simple trick that works well on any of the OS FP's or LA's (bleeder carb engines) of any size for the initial mid range adjustment is to insert a dressmakers pin or a large safety pin opened up into the bleed hole directly in front of the carb, with the adjustment screw backed well out. Now while holding the pin just screw the adjustment screw back in until you can just lightly feel it on the pin. Pull the pin out and you are done.

Recommend you get hands on help from an experienced glow engine operator.

John