I have the same set up on my RT and since it was a former authority bike I'm not sure what happened but darn near every bolt holding those engine guards on are all different :banghead In fact many bolts/screws/flubber are different and I've slowly been replacing them with the right size or at least matching. I think I've got one on a cyl that is stripped so I'll try to chase the threads, and keep watching this thread.
I do have a MIG welder but in the case of my bikes nicely painted engine jug I was very reluctant to put that kind of heat at work. On a 6mm hole if you miss the center kinda nasty looking repair,esp., when you weld occasionally & in tight spot. I actually "practice" before I do "need to be fussy" weld operations just to get my groove back.As if I ever had one,ha! I also have a jewelers small torch head that I considered but in the end decided to simply grind away the broken below surface & at the surface (whatever the hell you want to call them fasteners:)).
I too, was of the notion that above 1/4" the name changed but to be honest, in shop talk it's pretty common to be loose with some terms such as wood screw vs. deck screw-on infinitum! Such as, "go look in the "bolt box". I can see that around a few of the posters in this thread it would be a daily "gottcha grind"? on terminology- "Poor Paul", as he has to toe that mark all the time.:banghead
Cobalt twist drills are new territory for me & I wonder how much more brittle they are in use? I have such a "mother lode" of drill bits from years of on the job use that are common HSS I just never got into the cobalt ones but know they are commonly available & am buying a few now for touchy jobs. In a longer than "jobber length" bit how easy is it to break a e.g., 1/8" cobalt bit? I do have a few titanium coated bits that are fill in replacement bits but that grinds off @ 1st sharpening & doesn't seem too remarkable to me anyway.
Oh, did I say that I have the stomach virus AGAIN! after a ~ a week hiatus?
I never had a problem with those bolts, but then neither have I with any other fasteners on the motorcycle.
I guess its because I put anti-seize on all of them when I bought the motorcycle new.
I've had those chinese craftsman ezouts shatter just by tapping them into the hole before even trying to turn them. Junk. I now have a large assortment of carbide "reverse" twist drills which seem to work better.