What I did to my XS ('80 Special 2) today was something very stupid. Been reading about sealed-off mixture screws on here, decided on the spur of the moment, just before we were going out, to drill off my covers. Tackled the left side 1st, gently with a hand drill & then a pick - the cover flew off, thought I'd done well but couldn't see a screw, stuck a wire down the hole which went in a long way. We went out, all day I'm thinking oh crap - have I removed the wrong thing? Got home, checked the forum for a pic (& my carbs again with a torch this time) - yep, mixture screws are on top of the carbs, no covers. WTF have I drilled? Epoxied a tiny bb over the hole in panic mode which I hope will mean I have salvaged my carb.
Reminder to self: don't rush into something with half an idea of what you're doing, especially with a drill or power tool in your stupid hands.