I had a few carb bowl screws on my '76 550 that had weak or stripped threads in the carb bodies and I've seen a few posts about how to fix them ranging from using longer screws or red loctite or going up to 5mm screws or using a long screw and a nut where you can. The simple fix I used is to tap the holes for 8-32 x 7/16 screws. They are only slightly larger in diameter than the stock screws, you can run the tap in the holes without even drilling first, and you don't have to enlarge the float bowl holes. I even left the float bowls installed when I tapped the holes and they served as a guide for the tap. You will need a standard 8-32 tap to start the threads and also a bottom tap to finish them. I used stainless allen screws. It worked so good I did all the holes whether they were stripped or not. Going with this method, you still have the option of going up to 5mm size if you need to.
Oops, I almost forgot to blame all the stripped holes on previous owners!
