Second test flight attempt cut short

 June 26 2023

I attempted a second test flight but on climb out I was getting a popping and occasional backfiring from the engine.  My flight with one other Vans RV9 was cut short and I only completed one large circuit before landing as soon as possible.  My landing this time was much better but because I took my eye off of the centerline to look at my airspeed I began to turn and ended up doing a ground loop on the runway surface, thankfully no damage was incurred.  I have learned I need to make centerline and the flare the only things I do until slowed right down.

The popping noise was eventually identified as two of my lower spark plugs had lead balls on each which shorted them out and were not firing.  The excess fuel then exploded at times in the exhaust pipe.  I have bought a second set of plugs so I can have a clean set ready to begin any further test flights.  Being a newly overhauled engine it is also letting oil past the rings and into the spark plugs.  This is a real pain because I need to fly the engine hard for awhile to get the rings to seat properly.  Working on these small problems require more ground running to confirm problems have been rectified.  Oh well such is flight testing.