My motorcycle had been in an accident before I bought it. One of the bolts on the front left caliper keeps coming loose. The technician keeps torquing them but this one bolt keeps coming loose. Can someone explain or help

Well I don't think the crash had much to do with this, if the bike is old then over time the brake caliper has gone through a lot of force. So after so much force the threads have most likely been pushed/pulled out of shape. If the threads have been pulled apart then the bolt won't hold as well. That along with the vibrations from the engine, and the rattle from the street will cause the bolt to work it's way loose. I'd recommend using a thread locking compound. That should keep the bolt from coming loose

well i don't think the crash had much to do with this, if the bike is old then over time the brake caliper has gone through alot of force. so after so much force the threads have most likely been pushed/pulled out of shape. if the threads have been pulled apart then the bolt won't hold as well. that along with the vibrations from the engine, and the rattle from the street will cause the bolt to work it's way loose. i'd recommend using a thread locking compound. that should keep the bolt from coming loose

Thank you very much