locked up motor. PLEASE HELP!!

[Bigtim]

That is a real bummer dude.  Are you sru e you found what the cause was?  As I recall your friends dad owned the bike, Assuming he is trustworthy ask him about the fuel mixture.  If he had the bike for long it is unlikely that he mixed the fuel wrong.  THus you may still have a problem that will bite you in the future again.  I will say though I have ridden a ton of 2 strokes and that was the only reason i have ever seased piston.
Good job on keeping the bike upright.....
Now what is all this talk about detuning.  I love the adrinaline rush that violent hit causes. Don't casterate your machine, just learn throttle control.

I've heard of old fuel doing this type of intake side or 4 corner siezure.  More so in castor based than synthetics, but 2-stroke mixed fuel seperates after awhile and loses its lubrication qualities.  I'm hesitant about using fuel more than 2 weeks old. the stuff in this bike might have been months or years old.

[KXcam22]

can you post a pic of the crank spacing.  The rod must be in the center otherwise it sideloads the piston and causes the rings to snag in the port (another lesson I learned the hard way and was a PO assembly issue).  Its almost impossible for it not to be centered, so measure it and take a pic. You will like that K5. Once I started riding big bores I never went back to a 125. Cam.

[KTMEXC125]

yeah i'll try and put up a pic of it. the rod is center with the cases but its just that there is a little more space between the crank and the case on one side than the other. i cant wait to get this beast up and running. me and a bunch of friends went riding the other day and i was always wide open and looking for more power. and i want to be able to romp on crf450s!!!!

[KTMEXC125]

alright guys i got my 500 all back together and running over this weekend. the power is amazing! for the first 4 gears the front end wants to come up and in 5th the front end is super light! its even better in the woods. the power isnt as overwhelming as i thought as long as i dont do anything stupid with my throttle hand. my rear tire is wore down and it climbed muddy hills that my ktm or ttr 230 couldnt even manage with good tread. in my opinion the 500 is king of all dirtbikes