The thing is Scottly is that IF you overtighten a normal screw head the screwdriver tends to slip out before it either shears or strips the thread, it's a little like a failsafe. If it strips the thread it's usually because the thread was already damaged in some way. A small screwdriver bit in a socket helps with putting screws into float bowls or there is the special bit Snap On developed which grips the slots in the screwhead so it can be used a little like a socket head screw.
I've found the screws Honda used on the 500/550 etc type carbs are too long on the float bowl and too short of the carb top, if thread is exposed like it is on the float bowl screws these rust over time, dragging that through the thread in the body when you go to remove them can strip the thread right out of the body, exposed threads do nothing, they certainly don't exert any pressure. If you look at the threads in the carb top holes you'll spot the bottom threads have never been used and the amount of times I've found those holes stripped out is unreal, the spring washer doesn't help in that respect, a lot of them weren't even threaded to the bottom of the hole as well, I rethread them and punch out the loose bottom cap (sometimes that's there, sometimes it isn't) I then tend to use a 20mm screw in that hole instead of the 14mm Honda used. It pulls better and doesn't strip out the thread.
