Motorcycle Repair: 2003 raptor 660 camshaft, loose bolt, k n air filter

Question
i have a 2003 raptor 660 with a stock compression wiseco
piston,k&n air filter,piped and jetted. for some reason one of the
decompression cams on the camchain sprocket shot through my
head. could you tell me why this would happen. my email is
rustang000@sbcglobal.net. thanks for your help.

Answer
U lost me when u said "decompression  cams on the camchain sprocket".  In your motor u have cams, camchain, and gears attached to the ends of the cams.  What happended?  If it was a cam gear then I would say your cam was bad, or it had a loose bolt holding the gear on.  Did u over REV the bike?