If you have a melted rotor the cause is the cam bushing has rotated the cam end oil slot out of position or the bushing oil slot has become plugged.  This is not uncommon after a cam change.  The melting point of the ignition rotor is 430° F.  That means the end of the cam shaft has had to reach the melting point of the rotor.  When the rotor melts this changes the timing of the engine and it shuts off.  If the rotor is melted in such a fashion, do not change the ignition or continue use of the engine until the cam bushing has been checked or serious engine damage will occur.  When the problem has been repaired replacement rotors can be purchased from Spyke Inc.