As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTS TWO OR THREE HARD JOLTS FROM TURBULENCE WITH NEG G-FORCE. THE ENGINE WENT TO NEAR IDLE POWER. DISASSEMBLY OF THE CARB REVEALED THE PRESENCE OF A SILT CLOD IN MAIN JET. SUBMITTER RECOMMENDS PERIODIC CLEANING OF FLOAT BOWL TO REMOVE BUILD UP OF SILT. DRAINING OF THE BOWL DOES NOT REMOVE BUILD UP.