I've been fighting a rough idle in my 912ul. Between 1700 and 3000 the engine runs very rough. I sent the carbs to Lockwood, they rebuilt them and checked them on a test engine, ran fine. I put them back on my engine same thing, very rough between 1700 and 3000 rpm. I'm getting about a 150 rpm drop on both ing. boxes. Sync is dead on using gauges.
Here is the thing, I can get the engine to run a lot better at this rpm range by turning the idle mixture screws in about 1/2 turn from the factory recommended setting of 11/2 turns out. As I understand it turning the idle mixture screw in (clockwise) leans the idle mixture. The Rotax heavy maintenance manual has a note about changing from the #35 to #30 idle mixture jet if you experience rough idle and black plugs on the front cyls. ( I have both) Can you hurt the motor by having a too lean idle ?
Before I throw more money at new jets, has anyone any experience with changing out the idle jets?
Any ideas welcome.
My home airport is at 1200 ASL .
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