Just how high did it rev? If it went too far past 3600RPM it may have blown it's self up. Does the engine still have compression? Take the spark plug out and hold your thumb over the hole and turn the engine. If there is no pressure there
it may have broken a rod, or thrown a valve. STAY CLEAR of the spark plug wire when checking for compression or you will get a good jolt!
Rick
October 2005