My 24 oz OTS Ringmaster with OS20FP (or 21 for Dan's benefit) ABC/ABN(?) (Brett Buck setup which is unrelated to the problem), had previously run fairly well, maybe 85%--good enough for contests by my standards. During the last few flights the RPM started fluctuating both on the ground and in the air. The motor did respond to needle changes, though erratically, and there was no RPM drop when removing the ignitor (Thunderbolt RC long plug). I'm running Sig 10% with 20% half and half blended oil and 1% Randy juice added.
I tested the metal tank for leaks, cleaned out the needle body, checked the filter, replaced the fuel tubing and O-ring, silicon sealed the venturi/case seam and both sides of the needle body/case, and replaced the thrust washer which Larry "Eagle Eye" Wong astutely noticed was missing. No joy.
The sound of the motor was not right in addition to the erratic run, and the sound would change during maneuvers. After the last flight, I saw that the engine compartment and the underside of the nose were covered with black oil containing visible metal particles that had come out the front of the crank. My limited previous experience with black oil has been due to faulty or worn ball bearings, but obviously the 20 ain't got no ball bearings.
Any ideas? Thanks in advance.
Topic: OS20FP putting out black oil the day before a contest (Read 1118 times)