912 ULS runs rough at 2500 RPM

by Tony Garrett in 912 / 914 Technical Questions 13 years ago

2009 912 ULS with 500 hours total time. Engine runs rough at 2500 RPM (like one cylinder is misfiring). New Mc Farlane dual throttle cable and new spark plugs. Carb sync is right on at idle, 2500 and 3500 RPM. Engine runs very smooth at idle and above 3000 RPM. Periodically it runs rough around 2500 RPM. Other times it runs smooth at 2500. Mag check at 2500 and 3500 RPM yields 70 RPM drop on either mag.

Tony

Re: 912 ULS runs rough at 2500 RPM

by Roger Lee » 13 years ago

Roger Lee

131 5.38k 5.44k

Hi Tony,

Sounds like you have most things covered. Since it is intermittent and you have a good mag check my guess is a carb that doesn't control fuel as well as the other or a little roughness in air and the floats don't control the flow as well. I believe it is fuel delivery and maybe nothing you can or need to do if it is a slight roughness.Many engines have a spot in their rpm range they don't run as smooth as the rest of the rpms.

Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

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