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Thread: ESE's works engine tuner

  1. #35701
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    .
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    Blue line is WOT and the Red line is the throttle partially closed.

    I have always wondered why my fifty when it was tapped out on WOT going down the back straight, it would pick up speed when I closed the throttle a bit.....

    Fixed ignition timing, 24mm Carb, no power jet. Ignition and main jet optimized on the dyno with WOT wide open throttle runs.

    Any suggestions/thoughts would be welcome.

  2. #35702
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    Quote Originally Posted by TZ350 View Post
    .
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    Blue line is WOT and the Red line is the throttle partially closed.

    I have always wondered why my fifty when it was tapped out on WOT going down the back straight, would pick up speed when I closed the throttle a bit.....

    Fixed ignition timing, 24mm Carb, no power jet. Ignition and main jet optimized on the dyno with WOT wide open throttle runs.

    Any suggestions/thoughts would be welcome.

    Carburation wise if it picks up speed when the throttle is closed it's too lean.
    Quote Originally Posted by Katman View Post
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  3. #35703
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    Quote Originally Posted by TZ350 View Post
    .I have always wondered why my fifty when it was tapped out on WOT going down the back straight, it would pick up speed when I closed the throttle a bit..... Fixed ignition timing, 24mm Carb, no power jet. Ignition and main jet optimized on the dyno with WOT wide open throttle runs.
    Quote Originally Posted by husaberg View Post
    Carburation wise if it picks up speed when the throttle is closed it's too lean.
    I'm curious for a further explanation Husa. I'd rather expect it to be too rich. Then closing the throttle will lower the needle in the needle jet, making the mixture leaner.

  4. #35704
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    Got the DCI running with fuel into the DCI carb, seems to work...

    https://www.youtube.com/watch?v=iAf1gbWztT8
    "Success is the ability to go from one failure to another with no loss of enthusiasm.

  5. #35705
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    Frits, wouldn't closing the throttle also lower the amount of air entering, possibly making it richer momentarily somewhat like choke. Seems a catch 22 to me. But y'all are over my head half of the time anyway.

  6. #35706
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    Quote Originally Posted by Frits Overmars View Post
    I'm curious for a further explanation Husa. I'd rather expect it to be too rich. Then closing the throttle will lower the needle in the needle jet, making the mixture leaner.
    Can you not both have a point if we think for example a K 27 and a U needle eg U11
    No amount of experimentation can ever prove me right; a single experiment can prove me wrong.

  7. #35707
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    Quote Originally Posted by 136kg136ps View Post
    Frits, wouldn't closing the throttle also lower the amount of air entering, possibly making it richer momentarily somewhat like choke.
    I cannot rule it out, but I've never experienced myself that closing a throttle makes the mixture richer. On the other hand, I have often witnessed it getting leaner, sometimes resulting in seizures and crashes.

    Quote Originally Posted by 136kg136ps View Post
    ... y'all are over my head half of the time anyway.
    Let's be glad this isn't a swimming competition .
    Joking apart, I try to write simple and understandable and I like to think I was rather good at it in my previous life as a technical editor.
    But English is not my native language so there will no doubt be room for improvement. Just keep on asking if something is not clear.

  8. #35708
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    TZ350, is pipe temp the same for both runs?

    Those runs to me look like a pipe temperature difference.

    Or, it's really not making any more power as dyno is showing, it's just showing its revving higher... the leaner part throttle mixture is making pipe temp higher with 2 things.

    Leaner mixture = pipe temp increase

    Less airflow going through = hotter cylinder and pipe

  9. #35709
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    Quote Originally Posted by ken seeber View Post
    Got the DCI running with fuel into the DCI carb, seems to work...

    https://www.youtube.com/watch?v=iAf1gbWztT8
    Very cool! The concept for sure works, looking forward to see the continuation.

  10. #35710
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    Muhr , the effect you are describing is bound up in the fact that a KZ carb is way too small for a 50 Hp 125 engine.
    The airflow velocity is VERY high , thus the venturi depression created necessitates a very small main jet to achieve the correct A/F ratio.
    This also means the needle/tube combination has a very small annulus area at WOT.
    In fact a well tuned KZ will rev to 12,000 with no main jet at all - been there done that , not intentionally I might add ( dumb or even dumber ).

    But back to TeeZee dilemma , in this case the partially closed slide is decreasing the carbs airflow , way less than it is decreasing fuel flow from the emulsion tube nozzle , thus its (edit) :leaning the fuel curve over the top of the pipe.
    This is evidence of the fact that airflow thru the venturi continues to increase past the power peak , but less fuel is required at this point , as the combination of scavenging and trapping efficiency % is decreasing even faster
    If you had an electronic PJ this could be switched off , to achieve the required fuel curve past peak power - and this would increase the overev power exactly as per the red curve.

    But in this case I would suggest fitting a much bigger main air corrector jet , this will need a comensurately bigger main to get the peak power fueling/egt the same , but then the big air corrector will
    continue to lean off the overev fuel curve automatically.
    I have done the reverse of this several times to stop having to run a huge main to prevent an engines egt from continuing to run away past peak Hp , thus killing the peak power number with an over rich condition.
    The same can be done by using a flat line ignition curve past peak Hp , thus reducing the pipe egt/heat runaway, so reducing the need to add fuel to help cooling - not power.

    Again - proving that your engine is doing just that , with a flat line ignition .
    Always a dumb idea.

    Edit - i mistakenly wrote leaning - richening is correct - sorry
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  11. #35711
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    Quote Originally Posted by Frits Overmars View Post
    I'm curious for a further explanation Husa. I'd rather expect it to be too rich. Then closing the throttle will lower the needle in the needle jet, making the mixture leaner.
    The reasoning is from everyone from Bell to jennings and Gorr says the same.
    ALthough i have seen Cameron say the opposite once. i have had the same its always been cured by making the main or PJ larger.

    I'd suggest the reasoning is when you are backing off slightly but not enough for the overlapping needle to have much effect
    The backing off a little at the end of a long straight as Rob suggested and then running better. i assume there is still a strong fuel signal but less airflow so the momentary to lean condition is corrected from the too lean to the optimum. as the airflow decreased faster than i suspect the fuel flow does as its has more ineteria so there is a lag.
    if you were shutting off the throttle a longer way it would be on the needle. As the greatest area of a needle Effects, MIO is 3/8 to 3/4 throttle (unless of course the tapper is well off or the NJ is to small.)
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    i just read Wobs response maybe it can be both.
    Camerons has said a few times rolling off and if it picks up revs then the mixture is too rich
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    maybe depending on if the carbs optimal size its too rich if its undersize for MAx HP its indicates to lean
    Too small carbs auto en richen at peak revs where as bigger ones tend to lean out


    you could also try a taller or shorter hood on the Needle jet to alter the fuel supply.
    as bones harder to fix than fouled plugs Maybe Rob can try a richer jet first and see if it makes it worse?


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    Last edited by husaberg; 22nd July 2021 at 17:15. Reason: edited after reading wobs added cameron
    Quote Originally Posted by Katman View Post
    I reminder distinctly .




    Kinky is using a feather. Perverted is using the whole chicken

  12. #35712
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    First thing I always (sometime remember) do is pull the main out and see if the bike will run past 3/4 throttle, or if the needle jet is still the restriction.

    Actually I think this is where I came in probably on page 1 or 2 of this thread.
    I've been told. Dreaming`s free.
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    Everybody listen, do yours say, what mine says?

  13. #35713
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    Wob, yes true in the case I described. "Described" perhaps a little bit rich to call it
    However, I think the discussion that took place is interesting


    Here I think was a pretty interesting run. (Off topic above)
    Same:
    Carburettor
    Reed
    Crankcase assembly
    Head volume
    Piston
    Port duration (transfer time area not much difference)
    Exhaust (Ok, was probably no benefit to the blue)


    Clearly state what certain things can be more important ..
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    No amount of experimentation can ever prove me right; a single experiment can prove me wrong.

  14. #35714
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    Now I understand what I was confusingly trying to say above - the WOT run is going rich over the top.
    The partially closed run has the fuel curve leaner over the top , thus the extension to the power band.
    I have tried lowering the shroud , ( Dellorto make long and short variants ) as I thought in the small 30mm carb this would restrict airflow , but sadly no free lunch.
    Once it was rejetted to get the same egt , the power was identical.
    A retarding ignition or an electronic PJ would for sure work to pull up the egt past peak and increase overev power.
    Ive got a thing thats unique and new.To prove it I'll have the last laugh on you.Cause instead of one head I got two.And you know two heads are better than one.

  15. #35715
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    Quote Originally Posted by wobbly View Post
    I have tried lowering the shroud , ( Dellorto make long and short variants )
    Is it the same as atomizer? or is it something else you are referring to?
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    No amount of experimentation can ever prove me right; a single experiment can prove me wrong.

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