Dirtjunkie85 said:
What does it sound like to you guys?
Yep, sounds like it seized.
Unfortunately, there is no way to establish the extent of the damage until you take it apart.
I've burned a hole in a piston and had no other damage so that it was only a new piston and gaskets and I was good to go.
I doubt that your buddy will be so lucky. If it locked the rear wheel up it means that it seized hard enough to really jam things. This usually scores the cylinder wall which requires boring, sleeving, plating or some combination of those.
On a two stroke you are frequently lucky to have the damage limited to the cylinder. On a four stroke it is possible for the head/valves to be damaged in the process. If pieces of the piston have broken off and are down in the crank area you may have damage down there as well.
If the piston is still stuck (ie you can't kick it over) then you will have an additional problem that it will be very difficult to get the engine apart. I recommend that before you start tearing into it you remove the spark plug and pour some light oil into the cylinder and let it soak for a bit. Put the bike into a high gear and rock it back and forth to try to break the piston free. Be careful, if you get too aggressive you risk damaging the gear case and/or rod. But your alternative will be to remove the engine entirely and chisel the piston out.
Have you checked to oil? If the reason that the piston seized was because it ran out of oil then there is a very high probability that a lot of other parts are damaged as well.
Rod