Help with screw removal?

[VoltlovesBikes]

Hello all I recently started my first project bike a 1980 XS400 Special I picked up for $250. this bike has been green flag after green flag until now. I came across a stripped engine cover screw and tried to drill it out to place an extractor bit with no success. I then tried to cut a slit in it so I could screw it out also with no success. I am this close to calling it quits and selling it again but I really love this bike. Can someone help me please?

 

[drewpy]

as its steel in alloy, i'd weld a nut over it. the heat will break the corrosion and the nut will give good purchase to undo.

 

[RadlagerMike]

In this is the only screw with no succues then dismount all the others also the ones over the Lima and then wind the hole cover left and right and the screw will come loose

 

[avemachina]

Consider drilling the head of that screw off. Take the rest of the engine cover screws off, then use some vise grips to twist the remaining part of that bolt off (some heat or PB Blaster/penetrating oil might be useful).