Carbs - removing a stuck "choke" plunger
If a triple carb has been sitting for a while and the
"choke" (enrichener) has not been operated for a while, chances are you may be
looking at a brass "plunger" that is now stuck in its little "hole" in the carb.
If you're lucky and the enrichener cable is still attached (and not rotted) to the plunger, that may help you get the plunger out. First unscrew the cable adjuster from the carb body, get the return spring out of the way, and if you can, grab the cable that is still attached to the plunger with a pair of pliers (needle-nose works great), gently try to pull straight up on the cable, if the plunger budges even a little, smile, because there is hope. At that point, you can try spraying some WD-40 down in there or put some 50-50 (Acetone/ATF) mix in there and pull the plunger up with the cable and push it back down with a screwdriver, it may surprise you and come out.
If it doesn't easily come out, time to hit it with heat and the ATF mix. Fill the area with the mix, put the heat around the area where the plunger is, get the mix bubbling, and then pull up on the cable. This is where they will usually "let it go" and come out. You need to be careful so the cable doesn't just "pull out" of that slot at this point. If it does, then use the needle-nose plier to try and grab the "protrusion" on the plunger and use that to pull up on.
If it is still stuck and you don't have anything left to grab, then it is time to resort to the drill - start with a small drill bit and work up to the larger sizes. The threads on the carb body aren't very good and you need to be very careful and not touch those threads or they will have to be chased with a tap if/when you get the plunger out. Also, with the drilling, you need to be careful so you don't go through the plunger and damage the seat where the plunger rests.
The usual condition is for the plunger to be stuck in the hole, no cable attached and the slot either extremely widened out or destroyed (I think about 80% of mine have been that way).