I've seen this a lot of talk on the web on this subject, i've seen people weld things to the screws, drill the heads totally off, then not have enough screw to get vice grips onto, etc. I think this method it much easier. This may be "old hat" to some of you, but I figure this may help someone out there retain a little sanity:
Last night after giving up on trying to origami the carbs back on for the night (before I broke something
. I turned my attention to the stripped master cyl. screws. The left screw I was able to get out by pressing down on the screw really hard with a normal phillips screwdriver and it turned out. The right one however was too far gone. Looked like someone tried an impact driver after it was already stripped and just finished it off.
So I stared at it for a minute and had an idea: octagon peg in a round hole. I took a drill bit a little smaller than the diameter of the screw shaft and drilled into the head about 3/16" or so. Grabbed an allen wrench slightly bigger than the drill bit and tapped it into the new hole (GENTLY!), and twisted the screw right out.
Hopefully this may save someone out there some potential agony. Keep in mind that the screw is junk afterward.