If you go past two turns, the needles will be almost off the taper and will no longer respond well to adjustments.
Check your carb and clean it real good, especially the mesh strainer underneath the pump cover (cast metal). Use a good filter in the fuel line.
Also check your pump pulse line. It may need extra clamping on the nipples. I use a small ring (about 5mm wide) cut from the same line that I expand and shove over the line ends. Expanding can be done using pointed pliers.