Bummer!
I had the same problem on a Rm 125.
I researched welding, but would have had to split the case (not fun)
and I considered cutting out the broken piece, Drilling, retaping, and installing a bigger oil plug. But this compromised the integrity of the case and I didn't feel comfortable doing so.
I have always been a proponent of doing things the "right" way, and I was dubios of JB weld, which several people recommended, but faced with major surgury on the motor regardless, I figured I would give it a shot.
Worked GREAT! Wow was I amazed....
Grind with a die grinder or dremmel (even heavy grit sandpaper will work) about an inch in every direction around crack, if pieces are broken off (in my case) grind a rough fit on all the broken edges (helps give the epoxy something to bond to)
Mix equal parts of jb weld and glop that stuff on there, being careful not to get it in the case, or plug any necessary holes...
Let it dry for a few minutes, then smooth out the "patch"
let if cure for 12-24 hours and sand to finish if you want, (nobody looks under the bike but you!)
Retap if necessary and hit the trail!
Hope this gives you an idea, I was skeptical, but was pleasantly suprised!
Good Luck!
Chris
