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Hi Everyone 

i am seeking some advice on my 912 ul 100hp,

on Take off at full power engine sweet, then drop my RPM to cruise no issue all sweet, return to any sort of higher power setting it splutters almost simulating chalk on/ carb ice although both are not the problem.

Return power to a cruise setting 4800 RPM every thing fine, so i landed did full power up no problem, climb out again no problem soon as i drop to cruise RPM and then back to Higher power problem re-occcurs??

any sugestions Thanks.

  • Re: Splutter at full power in the air.

    by » 3 months ago


    Drop the bowls and look for debris and use the carb sync gauges to take a look. Clean and check any fuel filters. Do you have an electric pump? More info would be helpful.


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


  • Re: Splutter at full power in the air.

    by » 3 months ago


    Thank-you so much for your reply, i took off the carb bowls and noted the fuel in pilot side carb was full and overflowing? the other side seemed okay, both floats were floating ok and appeared to have no issues.

    In answer to your question earlier there is a electric fuel pump on the aircraft and there appeared to be no dirt in the bowl when removed, they did not seem to be  anything missing or detached on the underside of carb.

    Thanks.


  • Re: Splutter at full power in the air.

    by » 3 months ago


    Did you weigh the floats and do a carb sync to see if there may be an anomalies? If the one pair of floats are too heavy then the carb may be suffering from flooding? Just something to look at and rule in or out. This is cheap and easy plus it rules a problem in or out and reduces what the cause may be as you move forward.


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


  • Re: Splutter at full power in the air.

    by » one month ago


    I had a similar problem with my 912 ULS (150 hours since new) but more sever - climbing out at about at about 400 feet the engine started running extremely rough and I could not maintain level flight.  I was able to turn 180 and landed in opposite direction.  On ground the engine would only run smooth at and below approximate 1/2 throttle.  As I increased throttle I lost power.  Earlier I had noticed that little or no choke was required when engine was cold.

    Removed and put the carburetor floats on the scale.  The two pairs came in at 9 grams each so 50% above the specified 6 grams for a pair.  The floats were marked “B”. I check the relevant SBs for float removal and replacement but per the engine and carburetor serial numbers the SBs did not apply.  Clearly there are faulty carburetors in service not identified in the SBs. 

    32693_2_B1FC0945-C87B-4295-896B-E2C246F5EB6C.jpeg (You do not have access to download this file.)

  • Re: Splutter at full power in the air.

    by » one month ago


    Any float through the years can absorb fuel and get heavy. Back in the day when they were Mfg'd by another company they were more resilient to absorption and we rarely had an issue, but there was a company change and getting to composition 100% took some time for Rotax and others to get it sorted out. Hopefully now days that is behind us. It wasn't Rotax's fault they were just stuck dealing with it and they were up front about it (like everything) and helped people out. It was a tough time for some owners and service centers.

    It never helps to cry about spilt milk. It's already done and in the past whether it was one minute ago or last week. So the best way to handle things is get up, dust yourself of and move forward with either new solutions and progress for the future. You can't undo yesterday, but we can all contribute to tomorrow. :)


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


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