Engine hesitation 912 ULS

by in General Tech Discussion 8 years ago

I have a 912 ULS 100 hp. with 218 hrs. TT on it. I runs smooth as silk except whenever I reduce power to 3000-3200 rpm when turning on base leg. It has a small engine sputter/hesitation that lasts a second or two and then returns to normal operation. We did the 5 year hose replacement back in June and everything seemed fine at the time but this has just started to surface. Carbs were balanced back in June also. Other than this minor issue, the engine runs like a top through the full range of rpms! Just wondering if anyone might have any suggestions on what to look for or how I might correct the problem. Engine is installed in a 2009 Sport Cruiser. Thx. for any advice.

Re: Engine hesitation 912 ULS

by Roger Lee » 8 years ago

Roger Lee

126 5.14k 4.58k

There are many engines that have a slight rough spot passing through an rpm in that range. Usually I hear people say around 3200-3800. This could be normal or yes it could be something else. Since you have no other symptoms you may just want to keep an eye on it. Keeping just an eye on it is predicated on the fact you said there are no other symptoms. If you have any other symptoms like odd mag drops, temp changes or rough running gets worse or covers a wide rpm range then it's time to look more in depth. This rpm range is another reason for me to use 3300-3500 rpm to carb sync. When I sync them at 2500 and run the rpm up into the 3K+ range the needles usually want to split again. maybe this is all it is?

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

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Re: Engine hesitation 912 ULS

by Roger Lee » 8 years ago

Roger Lee

126 5.14k 4.58k

There are many engines that have a slight rough spot passing through an rpm in that range. Usually I hear people say around 3200-3800. This could be normal or yes it could be something else. Since you have no other symptoms you may just want to keep an eye on it. Keeping just an eye on it is predicated on the fact you said there are no other symptoms. If you have any other symptoms like odd mag drops, temp changes or rough running gets worse or covers a wide rpm range then it's time to look more in depth. This rpm range is another reason for me to use 3300-3500 rpm to carb sync. When I sync them at 2500 and run the rpm up into the 3K+ range the needles usually want to split again. Maybe this is all it is?

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

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Re: Engine hesitation 912 ULS

by itemprop='name' » 8 years ago

0 0 0

Thx. again Roger for the info. I also forgot to mention that the carb float bowls were removed to check for any debris and none was found. Floats are set correctly also and are functioning as they should. I will keep an eye on things and note any changes. Appreciate your feedback, extremely helpful as always.

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Engine hesitation 912 ULS

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