912 low on power
in 912 / 914 Technical Questions
7 years ago
My 912 UL with 1340 hours on it will only run at around 4800 RPM while flying. Until a couple of weeks ago it would run up to 5400 at about 3/4 throttle. I checked the mags, they seem normal. I removed the carb. tops and checked the diaphragms and needle valves, they seem ok. I pulled the bowls and the gas flow seems about a cup a minute from each needle valve. A compression check showed about 135 to 140 on all cylinders. Spark plugs have a gray lean burn look. I did a mechanical adjustment on the throttle levers, they seem to be in sync. I disconnected the cross over tube, plugged the intake's and put vacuum gauges on the bottom ports of the carbs next to the mounting brackets. When running this way it shakes a lot and the gauges jump making them hard to read and the left carb spills gas out the overflow. I'm not sure how to proceed.
