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Thread: Exhaust Gas Temps

  1. #1
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    Exhaust Gas Temps

    Hi all,

    My sense is that my 582 is running fairly rich, confirmed by carbon build up between de-cokes, high-ish fuel consumption and low EGT readings.

    I'm prepared to experiment with main jet size but I can't find any published info on what optimum EGT figures I should be aiming for...... can anyone enlighten me?

    Many thanks,

    Phil Cater

  2. #2
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    Exhaust Gas Temps

    http://www.challengers101.com/ExhaustGasTemp.html take a look at this. It's probably the most comprehensive write-up on EGT iv read. Before altering the jets I would certainly take heed of the information on plug reading.

  3. #3
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    Exhaust Gas Temps

    If your engine has a few hours under its belt I'd look to change the jets needles etc (for standard size items).
    Also when did you last clean the air filters??
    Regards

  4. #4
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    Exhaust Gas Temps

    Presume your carb needles are set in correct slots?

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    Exhaust Gas Temps

    ....and propeller is at correct pitch

  6. #6
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    Exhaust Gas Temps

    Thanks for the suggestions everyone.....

    The prop pitch is correct and the filters were recently cleaned. The spark plugs confirm that the engine is running rich but I've yet to check the actual jetting....I suppose I should start by checking that the main jet is 'standard' (165) and if so, lowering the needle (11G2) to see what effect it has.

    I suppose I shouldn't complain about low EGTs - usually high EGTs are the problem that people seek a cure for!

    I just feel that I should make the engine as efficient as possible whilst saving a bit of fuel in the process - I obviously don't want to run the engine too 'hot' though, hence my enquiry as to optimum temps....

    Thanks again,

    Phil

    P.S. I've found this chart which is useful: http://www.rotaxservice.com/documents/2STref.pdf

  7. #7
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    Exhaust Gas Temps

    I wouldn't start lowering needles until it is confirmed that the correct ones (jets and needles) are fitted.

    Also are the jets/needles worn?

  8. #8
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    Exhaust Gas Temps

    ....is the choke leaking?
    Is the carb floats at correct setting (check that they are not sinking - re latest identified problem with rotax floats)?
    Does the float valve actually shut off the fuel when the float chamber is full?

  9. #9
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    Exhaust Gas Temps

    I do remember reading somewhere that the uk tend to set the rotax motors to run slightly rich. Not sure of the reasoning for this and I'm not going to start surmising.
    Paul I thought the float thing was only for 912's?

  10. #10
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    Exhaust Gas Temps

    I would be very carefully before I would start to change jetting away from the Rotax std set-up...it should be fine bar maybe a changing the neddles down/up a slot.

    Check all you jetting and needle settings is as per the manual...and that nobody has been experimenting in the past with your engine if your not its first owner.

    Getting to weak can be dangerous as I am sure you know.

    What static RPM are you getting....to course a pitch will make the mix appear richer giving a cooler EGT and the opposite if its to fine.

    Max book EGT is 650C I run my 503 at around 600C...what does yours indicate.

    Nick.

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