Motorcycle Repair: s&s 113ci eng. cyl. heads, plug holes, valve seats

Question
i have a1997 113 s&s that stared to run rough when i stripped it for repair i found ablown head gask. back cyl. and both cyl. heads have cracks through the spark plug holes and up under the valve seats. is this a comon thing or ? this eng. only has 5000 miles . it ran great till it blew the head gask.  

Answer
I have never heard of a S&S motor doing this. About hte only thing I can think of that would cause this is running the motor to retarted or not enough octane in the fuel and causing pinging or predetonation.
You might want to contact S&S and ask them
Mike