I have the same carb on my snowblower. Worked great until today. Won't start. I gave it a quick cleaning, and still nothing. I am going to give it a much better cleaning tomorrow. My question is, to the left of the needle valve, in the picture is another screw. The needle valve has a spring on it, the one to the left does not. How tight should the one on the left be tightened?
In the picture above, the screw on the left is the pilot jet.
It is not an adjustment screw and it needs too be snug. It is soft brass and cant be reefed on too hard or it will distort.
It has a very small passage that runs from the tip where it connects with 2 larger passages on the sides.
That passage sometimes needs too be cleared with a very thin wire. When its plugged, surging is the main symptom.