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I have an intermittent misfire on the 912 ULS fitted to my 601. This happened previously and eventually it turned out to be a slack earth wire on one of the SMD's. Since then it has been running just fine, until last weekend, just after take off you can feel it misfire, does it for a few mins then seems to clear up.
I have checked all the usual suspects, sinking floats, contamination, rubber carb flange, spark plug and gaps etc. I cannot seem to replicate it on the ground, on mag check around 150 RPM drop on both circuits. Full power is very steady and no issues.
The only thing I found is on the bottom of cyl 3, the plug cap was not fully engaged onto the plug, could that cause this problem?
Possibly? Think you might need the Carburetors Sincronizing?