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Thread: rotax 447 problems

  1. #1
    neo
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    rotax 447 problems

    I just got a rotax 447 and it will run like a champ without the prop but will stall when i give it gas when the prop is on it. can anyone help?

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    Re: rotax 447 problems

    Quote Originally Posted by neo View Post
    I just got a rotax 447 and it will run like a champ without the prop but will stall when i give it gas when the prop is on it. can anyone help?
    Sounds like a fuel problem,maybe too lean when under a load. I would clean carb and try it again.You could try choking it as you throttle up if it stays running most likely fuel starvation. Good Luck Randy

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    Re: rotax 447 problems

    Neo,

    Most likely the problem is that you have the idle mixture set to lean or you have the idle RPM set to low or both.

    If you have a owners manual for the engine, look to see what the recommended idle RPM should be. Otherwise, I would set the idle RPM at 3,000 to 3,500. These engines do not like lower RPM.

    The idle mixture adjustment on Bing carb is an air screw. As you screw the mixture adjustment screw out, the idle mixture is leaner. (more air - less gas).

    With the engine warmed up and at idle, try adjusting the air adj screw in 1/4 turn at a time. Allow some time for the adjustment to take effect. Have someone watch the tach as you do this. You want to turn the screw in or out until the engine reaches the max idle RPM. Then you turn the screw about 1/8 to 1/4 turn in. This will give a slight rich mixture and should cure you engine wanting to die on opening the throttle problem.

    If the above does not work, I would disassemble the carb, clean all the passages and check the float height. If the fuel in the bowl is to low, it could cause problems.

    Richard

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    Re: rotax 447 problems

    If you set your idle to 3,000 - 3,500 rpm, you'd better have 'good' brakes.

    As a Rotax repair station for the last 12 years, the first thing you should do is set the carb settings back to stock - meaning the jets, needles, everything. Then see how it runs. If the engine has not been run regularly, might not be a bad idea to do a carb rebuild kit either. Also check the fuel pump pulse line is not cracked or collapsing.

    All above said, the 447 is temperamental on idling compared to the 277/377/503/582's. Standard Rotax idle should be around 2,000. However I've found all the 447's on aircraft I've built (around 30 aircraft with 447's) it likes to idle more around 2400 rpm. Anything lower then that, the 447 after idling for 30 seconds or so, the rpm will drop off and the engine will want to die. This seems to be only for the 447's though.

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    Re: rotax 447 problems

    I have the same problem, did any of the suggested solutions fix this??

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    Re: rotax 447 problems

    fuel consumption is about twice as it should be on my rotax 447

    any suggestions?
    Last edited by King Chicken; May 20th, 2013 at 02:46 PM.

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    Re: rotax 447 problems

    Has it ever run ok with this prop,

    Just wondering if maybe it has to much pitch for the engine???

    Nick.

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    Re: rotax 447 problems

    Nick

    I'm just getting it flying, about 3 hours on it.
    RPM's are where it should be for climing out. 6450
    All temps are within normal range. EGT 350 CHT 1050
    Just burning about 6 gallon a hour.

    Larry

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    Re: rotax 447 problems

    6 galls per hour WOW thats heavy...1050 is a bit cool in my book suggesting an over rich jetting...which could also cause your bogging on opening the throttle,

    Think I would strip the carb and check all the jets and needles to make sure there at the book setting.

    Nick.

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    Registered User King Chicken's Avatar
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    Re: rotax 447 problems

    Ok I'll check it out
    thanks
    Larry

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    Re: rotax 447 problems

    What kind of RPM is it cruising at and is that 6 gall fuel burn at cruise RPM,

    If you dont know what your STD jetting should be...I can point you to some on-line web site that should give you that info.

    Nick.

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    Re: rotax 447 problems

    6 gph is absurd for a 447! If it was running that rich it should be fouling plugs horribly. I would look for a fuel leak somewhere between the fuel pump and the carburetor. I had excessive fuel consumption on my Cuyuna and it turned out to be a pinhole leak in the fuel line right where it clamped to the carburetor inlet. It was hard to find because it only leaked when the engine was running, of course, and was swept away by the breeze from the propeller. I eventually found it by squeezing the fuel line when the engine wasn't running.

    Dana

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    Re: rotax 447 problems

    Rminds me of a 2 stroke outboard motor I had some years ago...always ran fine till one day it would only run at higher RPM and used lots of fuel in the process,

    Scratched my head with that one...convinced it was a carb prob...turned out to be the impluse fuel pump...it had a hole in the diaphragm and it was sucking neat fuel direct into the engine...by-passing the carbs....the motor could only handle the excess fuel at high RPM.

    Nick.

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    Re: rotax 447 problems

    Cruising around 5500 or so, plugs look good and are new
    got to thinking and I was playing some as well, diving and climbing
    Dana I'm thinking like you, just can't find the leak
    going to tear it down and find out what is inside carb
    Thanks for the suggestions. I do appreciate it.
    I am a Private Pilot and I fly an older Phantom, and have about 400 hrs in Ultralights.
    Thanks again for your suggestions.

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    Re: rotax 447 problems

    Hello everyone! Friend of mine has QU MXL rotax 447, single CDI. CDI is broken and we are looking for used one or same ROTAX 447 with warranty...Any suggestions, please...

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