carb cleaning help. please!  By  vanillagorilla (Read 696 times)

I would like to see a picture of it, to see what you can do with it, but in general lubrication and heat are two things you can try.  Spray it with cleaner, then put on some PB Blaster, WD-40, or other penetrant.  Let it sit for a few minutes, or even a day if it needs it.  If it still won't come out, and there is nothing near the screw that would be damaged by heat, use a tiny torch to heat area right AROUND the screw.  This will cause it to expand and possibly break the bond holding it to the carb.  If that does not work then heat the screw as well.  After it is warm, try to break it free.  If it doesn't come out, put some more penetrant or some paraffin wax on it to let the wax get down into the threads.  Let it cool.  "Rinse and repeat."

If all else fails, you're looking at extracting or drilling the screw out.  A left-hand drill bit is often useful for small screws.  As it goes into the screw, the removal of material tends to help the screw loosen a bit and, because you are turning left, the drill bit will spin the screw out.  If that doesn't work then put an extractor in the hole you drilled and try that.  If that doesn't work then carefully drill out the screw, with the same sized bit you would use to tap that size of threads with, and then pick out the threads left in the hole.  After that, run a tap through the threads to clean them up if needed.

There are also methods of welding a bolt onto the back of your screw, which simultaneously heat it.  This CAN work but is often touchy on small screws, especially if they are brass.

If the carb is cheap, then obviously you can avoid a lot of trouble by buying a new one, but you have little to lose in trying all of the above methods.