Spark plug problems
I have got a DJ 72 V-2 single cylinder, side exhaust engine. It is just the usual engineering like DA, DLE, etc.. except for the stroke/bore ratio being slightly greater than its counterparts. Performance wise I am really satisfied with it. However there is something that makes the spark plugs (NGK CM-6) go bad very fast. At first you notice that starting the engine is a bit more troublesome. A couple of gallons of fuel later it gradually starts to get flooded, then it back fires and at the end it just refuses to fire up. It has happened four times in a row; 2 NGK, 1 Champion and 1 DLE CM-6, at least that is what was printed on the plugs. I do not believe in coincidences. By now I learned the lesson of course and I always keep two spare brand new NGK's in my flying box.
Additional clues: Unlike the new ones the "exhausted plugs" show no or erratic conductivity between the two ends of the electrode. Fuel mixture 35:1 (Klotz), RCEXL high voltage and factory set ignition timing.
Does anyone have an idea of what can cause such a thing?