Stripped A/F screw

[Guest]

I have a set of 550 carbs and managed to get 3 of the 4 mixture screws out for cleaning. The PO mangled the last one and now its stuck. Anyone overcome this before or know someone who can help?

[RichDesmond]

I have a set of 550 carbs and managed to get 3 of the 4 mixture screws out for cleaning. The PO mangled the last one and now its stuck. Anyone overcome this before or know someone who can help?

What type of carb? I think the early 550s had slide throttle carbs, later ones had CVs.

[Nessism]

A thin dremel cut off disc can be used to slice down into the carb body and make a new slot. A bit ugly, but common procedure. Google search "stripped mikuni pilot screw" and look at the images.

[LAB3]

My first idea would be to put a dab of super glue onto the head of a small nail and see if that works.

[Mr.humbucker]

The dremel cut is the best option but I suggest adding some heat/torch to the area first to help free the threads as they were likely stuck in the first place hence the mangled screw slot. Also a tight fit full width slot screw driver blade is a good idea. Good luck!

[jordandenmark1]

its from an 80. the CV Carbs.

[KEITH KRAUSE]

I've removed a couple of stripped screws this way: take a very small punch with a sharp tip, place it near the outer edge of the screw but not contacting the carb body, hold the punch straight up and tap the punch several times with a moderate/firm force. Don't let the punch tip move. Hit it a little and hit it harder as you go. You're trying to achieve a small indentation. When satisfied, slightly angle the punch and hit the punch to loosen the screw a little at a time. This makes the punch a simple impact tool. It's worked for me but sometimes the punch just doesn't "seat" and you get nowhere. Some patience is needed when you're trying to seat the punch.
Only other thing you can do is as Ed said. The usual problem is the factory wipes some sealer on the screw to discourage adjustments and the sealer jams up the threads if a poor fitting tool is used. Heat can help if you apply it right. The carb body material will heat up faster than the brass screw and that can help decrease some of the friction. Maybe try a quality penetrating fluid too or in combination with the heat or method I described.