Rough running Between 2400 & 2900 RPM on 912ULS

by john kennedy in 912 / 914 Technical Questions 13 years ago

I have a 912uls that has developed rough running between 2400 & 2900 rpm as if one cylinder has shut down. I have balanced the carb's, fitted new metering needles & jets to the carby slides checked floats & float levels, balanced the prop, fitted new engine suspension rubber mounts, new spark plugs. the engine runs fine through the rest of the range.

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Re: Rough running Between 2400 & 2900 RPM on 912ULS

by jan kerstens » 13 years ago

jan kerstens

34 131 5

Hello,

I have the same problem with a brand new ROTAX912 UL and still did not sort out the problem sofar.

Please check if the muffler is not touching the engine support structure. There has been some issues for the FK9 ultralights in the past.

Did you do some modifications on and around the engine recently?

Jan

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Re: Rough running Between 2400 & 2900 RPM on 912ULS

by john kennedy » 13 years ago

john kennedy

1 6 0

Hi Jan, thanks for your input, no every thing is fine around the engine and no i have not made any changes, the aircraft came to us for service with a report of the rough running, we have been servicing this machine since it was brand new and it has about 600 hrs.

Regards John.

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Re: Rough running Between 2400 & 2900 RPM on 912ULS

by jan kerstens » 13 years ago

jan kerstens

34 131 5

Hi John,

Just to generate some possibilities:

1. did you check the rubber carb mounting flanges for cracks?
2. did you run the engine with and without fuelpump?
3. did you replace all the fuel filters?
4. did you check the fuelpressure at the vibration rpm range?
5. did you check the attachments of the engine support structure to the fuselage?

Regards Jan

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Re: Rough running Between 2400 & 2900 RPM on 912ULS

by john kennedy » 13 years ago

john kennedy

1 6 0

Hi Jan, only thing that I did not do was check the fuel pressure in the rough range, so I will give that a go and see what happens,

Regards John.

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Re: Rough running Between 2400 & 2900 RPM on 912ULS

by jan kerstens » 13 years ago

jan kerstens

34 131 5

Hello John, did you change the position of the circlet of the carb needle to the third notch from above for the winter? With this position the engine will run rougher in summer time.
Regards Jan

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Rough running Between 2400 & 2900 RPM on 912ULS

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