Carbs - how not to mess up the needle jet
Another item to be concerned about when tearing down a
carb to clean is the needle jet - the threads on it where the main jet threads
into it CAN get damaged if not carefully removed. The main jet is screwed into
the bottom of the needle jet - the common thing to do is put the carb upside
down on your bench, take a larger straight bladed screwdriver, unscrew the main
jet about 1 turn and then lightly tap the main jet and the needle jet should
move a little. That's what SHOULD happen in a perfect world. If the carb hasn't
been serviced for a while (like 30-40 years), you just may find the needle jet
did not move at all when you "lightly" tapped it.
To help things along, I have taken a straight old "stout" (thick shank) nail that has a head just slightly smaller than the outer dia. of the needle jet and ground off one side of it "flat" so it will clear that little brass "locating peg" that protrudes into the side of the alum. "tube" that the needle jet sits in.
So, first you unscrew the main jet all the way out, remove the brass washer under the main jet and then place the head of the nail on the end of the needle jet so the "flat spot" will clear the locating peg, and then tap on the point of the nail to get the needle jet to move and come out. You'll again want to be careful as the needle jet is coming out, since you don't want to damage the "hood" (choke) that sits on the other end of the needle jet, as that can bend quite easily.