What was found
(CAN) THE AIRCRAFT WAS EXPERIENCING BRIEF DURATIONS OF ENGINE SPUTTER MOSTLY ON CLIMB OUT. TROUBLESHOOTING COULD NOT ISOLATE THE FAULT AND GROUND RUN COULD NOT DUPLICATE THE PROBLEM. THIS ENGINE IS EQUIPPEDWITH A LASAR IGNITION STC WHICH HAD A SIMILAR DEFECT PREVIOUSLY. THE LEFT MAGNETO WAS CHANGED BUT THE DEFECT FREQUENCY AND DURATION INCREASED. THE SUBSEQUENT REPLACEMENT OF THE RIGHT HAND MAGNETO REC TIFIED THE PROBLEM.