I'm doing a lot better. Some may scoff at the idea and before I mention it, I have to stress the key word "Clean". I've had a 100% success rate with JB Weld on many different parts including interior engine components. If you don't have the time and patience to thouroghly clean the part and area to be repaired don't attempt it because it will most likely break.
I'm sure you're reffering to the mounting hole at the bottom of the motor. If it broke off on the road and it's gone use masking tape to make form. If it did'nt and it's partially cracked or broken and the break is thru the hole area which is most likely the case, wiggle it back and forth with vise grips or good pliers to break it off. If the break is above the hole I would think twice about breaking it off. If it is broken thru the hole and you have the piece you can reattatch it but, loosly so, that you have 1/16" to 1/8" of JB Weld in the joint. I experimented with it before using it on a part to see if my therory was correct and it was. I'm a carpenter by trade and when you glue 2 pieces of wood together you apply the glue to both (which should be the same with JB Weld) and clamp it together squeezing all the excess glue out. JB Weld has no strength applied in this fashion. I tried this first on a part and snapped it apart with my hands. Then I put it back together loosely with about 1/16" filled gap and it was strong as can be. So, if you have the piece, use a piece of masking tape to make a craddle, holding it in place. Keep and eye on it for about an hour. This is about the time it takes to set depending on the temperature. Again I can't stress enough that the pieces have to be absolutly clean and your confident in what your doing. Otherwise as Dad use to say, " If your not going to do it right the first time, don't do it at all". I would wait 72 hours for the epoxy to completely cure before attaching anything to it.
After about 8 hrs or over night you can file and or sand it to shape it. If the piece is gone and there is a portion of the hole left, file and or sand the JB Weld to where it is the same thickness. If you have a set of calipers, they're really helpful. If not and you have a good adjustable (cresent) wrench use it as a gauge. The more precise you are the better the stronger the results. Slightly smaller would be better as it allows the tab to be squeezed on the aluminum when the bolt is tightened.
I wouldn't hesitate on my bike but, if you have doubts, DON'T DO IT. Disregard this post and carry on.
Two things I forgot to mention:
#1 Wash the front of the engine with something like simple green or even liquid detergent that breaks down greese and oil, let dry or blow dry with "Clean" compressed air, then wash the area and broken piece if you have it with acetone. This not an option and essential to achiving maximum results.
#2 It just occured to me you have an aftermarket exhaust which may be very close to the mount point. Note the picture of my bike, the header is above and clear of the holes and being heat rises is a plus. If it is close I would incorporate a heat shield fabricated from sheet metal, an old pie pan or steel paint roller pan if the header is not to terribly close, in which case ABORT and continue the quest of an alternate means of mounting the pegs.
Although this post may not have been help to you, it could possibly spark an idea or help someone else.
P.S. If I left anything out or unclear on some point don't hesitate ask.