How did it shear? Was it tight to wind in from the start, ie you threaded and forced it in, or did it seat home easy enough and you gave it too much muscle over torquing and then in broke. If its the former your going to most likely have to drill through slowly carefully patiently a few times starting from a small drill bit and increasing sizes until it dislodges, the thread will fubar and you will have to helicoil it. If its the later then maybe using a small reverse drill bit drill in slowly and possibly it will catch and wind the bolt out for you. The kawa bolts are not that tough so any decent quality drill bits should be sufficient.