xkevenx said:
you take out your entire engine,drill it out or you could try to weld something on the bolt so you can turn it out...
I would recommend taking it to someone that tig welds and do what xkevenx said. Weld a bead to the broken part of the plug and drop a small nut on the bead and weld it to the bead. Then, using a wrench or socket on the nut, unscrew the plug. And you won't have to remove the engine, just lay the bike on its side.
Be sure to use a tig welder since they weld very clean and don't produce spatter. Wire welding will produce spatter and clog the threads making it hard to remove the plug.
If you try to drill a hole in the plug for an easy out, the drill could catch in the metal and screw the remainder of the plug into the gearbox. If that happens, you will have to split your engine cases to remove the plug.
The reason the head snapped off of the drain plug is most likely the over tightening of the drain plug and not using a new sealing washer when you change your oil. When you use a new sealing washer, (crush washer) you don't have to over tighten the plug to seal it. Go to your local dealer and buy a handful of new sealing washers for the next time. They are very inexpensive and can save you a lot of trouble.
Just my $ .02