As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) UPON INSTALLATION OF CYLINDERS AFTER OVERHAUL OF CRANKCASE THE EXHUAST VALVE IN ONE CYLINDER WAS NOTICED TO BE BADLY CORRODED AND ERODED AT THE NECK OF THE VALVE.ALL OTHER EXHAUST VALVES WERE INSPECTED SERVICEABLE AND THE ONE WILL BE REPLACED. IT SHOULD BE NOTED THAT WHEN INSTALLED, EVEN WITH A BOROSCOPE THIS AREA CAN NOT BE INSPECTED.