My Engine Type is ROTAX 912ULS 2 -01 and S/N is 6785675.

I have a Big issue on my carburetor.
The right hand carburetor will overflow every time.
Then I disassemble it, One of the float is going down compare with other one obviously.
I think that why overflowing.

And Another problem is The RPM dose Not follow the Throttle lever forward movement.

What is more, the SparkPlug on the wrong side
carburetor is getting Black and Wet obviously.

Could you tell me How I can solve these problems ?

I’m expecting your early reply !

Thank you.

Toru
  • Re: Carburetor overflow

    by » 6 months ago


    Maybe a bad float. Take both out do a visual and weight check. Pretty sure there was a Service Bulletin on the floats.

  • Re: Carburetor overflow

    by » 6 months ago


    It could be the floats. Take them out as a set on each side, dry them off and weigh them as a set. The max weight is 7 grams. If a set weighs more than this replace them as a set. The other thing this may be is the float armature is out of adjustment. To correct the armature height your carb must come off and be help upside down.
    Are the plug really wet black or dry black? Before you overly worry about this make sure the carb issue is fixed first. Dry black can be normal if you have been idling and especially at low rpm.

    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-574-1080 Home (TRY HOME FIRST)
    520-349-7056 Cell

  • Re: Carburetor overflow

    by » 6 months ago


    1.strip CLEARANCE is also important .
    2.FLOAT weight not more than 7 grams.
    3. bowl tighten torque 5.5Nm.
    4. bowl gasket proper setting.

  • Re: Carburetor overflow

    by » 6 months ago


    Hi All.
    Thank you for your advise !
    I replaced the both float, bowl gasket and every spark plug.
    But it doesn't come fine.
    I still have a fuel leak on the lid of the bowl.
    It's a small amount of leak though,But it leaks certainly.
    Does anyone have an idea from where the leak comes ?
    And ,How i can stop it ?

    Thank you.

    Toru.

    Thank you said by: 姓, xìng wang

  • Re: Carburetor overflow

    by » 6 months ago


    if carburetor bowl deform, that may cause of leakage.
    strip CLEARANCE is also important role in stopping fuel.

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