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Thread: Exhaust Gas Temps

  1. #21
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    Exhaust Gas Temps

    Thanks Nick.....what you say is even more depressing though, since the gauges should've been reading higher than the ACTUAL temps, being as it was so chilly yesterday; furthermore these gauges will continue to over-read until we get a Summer heat wave!

    I just can't understand why so many pilots are struggling to keep their EGTs within upper limits whilst I apparently can't get mine high enough to be anywhere near efficient....

    As an aside, I remember reading as a lad when I was interested in getting the best out of my two-stroke motorcycle that 'reading' your plug colour is only useful after doing an engine 'chop' during a full throttle run (ie. a sustained period on main jet).....removing the plugs after the engine's been idling for a couple of minutes would not be representative.

    Oh well, maybe next time at the strip!

    Cheers,

    Phil.

  2. #22
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    Exhaust Gas Temps

    Check your idle jet size as well. Are you fitted with an intake silencer?

  3. #23
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    Exhaust Gas Temps

    Hi Dominic, thanks for your input.

    I think you probably mean my needle jet size - I don't think my idle jet will have much influence on my EGTs in the cruise - and yes, I will check it just as soon as I can dismantle the carb properly without my fingers turning to icicles. It may have to wait a few weeks.

    I don't have an intake silencer fitted but I do have an after-muffler which, according to the Rotax documentation, shouldn't affect the carburation but I suspect that it must do, a little. Common sense tells me that strangling the flow of gasses would require less gasoline
    (ie. smaller jets) to match the diminished air throughput.

  4. #24
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    Exhaust Gas Temps

    Is the engine making its full static RPM...low RPM = rick mix cooler EGT.

  5. #25
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    Exhaust Gas Temps

    Thanks Nick, Yep she's making the required 6000rpm (plus!) static revs - in fact the motor is really sweet if a little noisy compared with other 582s at my strip - maybe I need a new silencer although there's no external evidence of that other than a fine coating of rust; no leaks as far as I can see......Perhaps the internals are shot. But then why would it make as much power as it does!

    I can't complain about the power, I'm just looking for a little better fuel economy and less carbon build up between services.

    Oh well - I'll continue tinkering!

    :-)

  6. #26
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    Exhaust Gas Temps

    Mmmmm less carbon between services...that could be a clue...with modern oil you should get very little...that maybe a sign of a quite rich mixture.

    Is it oil injected??

  7. #27
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    Exhaust Gas Temps

    No, it's pre-mix at 50:1.

    As I said at the start of this thread, my problem stems from an over-rich fuel/air mixture, as evidenced by ridiculously low EGTs and high carbon deposits. I'm working towards leaning everything off.....

    I only hope that my EGT instrument is accurate cos that's what I'm relying on to tell me when I've hit the ideal mixture (that and the smooth running of course).

  8. #28
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    Exhaust Gas Temps

    Sorry I forgot.

  9. #29
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    Exhaust Gas Temps

    Best to check your CHT system by another means before going too far on the mixture...
    You could use a IR non contact thermometer.. around 10 on flea bay, but I have found it difficult to get accurate readings on the cylinder head...... and my arms are not long enough for use in the air:-)

    In the past I have used

    http://www.ebay.co.uk/itm/Black-Type-K-Digital-Thermometer-TM-902C-Thermocouple-Probe-50-to-1300-/281901918185?hash=item41a2a9e7e9:g:qFUAAOSwX~dWjB9 u

    3.56 inc postage
    plus a 14mm under plug K type thermocouple

    http://www.ebay.co.uk/itm/CHT-K-type-Thermocouple-Temperature-Sensors-for-Cylinder-Head-Temperature-14mm-/380900301451?hash=item58af6d5a8b:m:mSbuOF0PZZZmNoK JR6BUNPg

    May be worth also getting an EGT probe (needs minor mod to fit the rotax fitment)

    http://www.ebay.co.uk/itm/EGT-K-Type-Thermocouple-Temperature-Sensors-with-Clamp-Bendable-Probe-Special-/381561443278?hash=item58d6d593ce:g:yhwAAOSwmmxW2gV k
    6.77

    Hope it helps

  10. #30
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    Exhaust Gas Temps

    Wally what handy gadgets...just ordered the egt probe and meter...I am just about to set up an old British 2 stroke motor bike and I have been wondering how I can look at how its running...should be just the job...I suppose I should also get an under plug sensor as well.

    Nick.

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