1972 Combat dont go up 3300 rpm

Discussion in 'Norton Commando Classic Motorcycles' started by pierodn, Oct 11, 2017.

  1. pierodn

    pierodn Well-Known Member

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    Hi All.
    The bike ride very well until 3300 rpm, but dont go up.
    Bike has a new Pazon and stock carburetors overhaulled.
    What i must ceck?.
    Thanks.
    Piero
     
  2. lutewizzard

    lutewizzard Member

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    Did you check the PAZON is advancing properly, to about 28 degrees BTDC at 3000 revs.
    Does it improve/get worse if you release the choke lever (choke in working.
    Does it improve when rolling back the throttle a bit? Are the jet needles properly installed?
    It is possible to have the tip of the needle to not enter the jet tube with similar results.
     
  3. pierodn

    pierodn Well-Known Member

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    Hi.
    Pazon is 31 degree to 5000 rpm, strobo light.
    Throttles needle with central clip, needles jet 106 and main jet 220 are amal new.
    Choke is all tight.
    Under 3300 runs great.
    Thanks.
    Piero
     
  4. concours

    concours Well-Known Member VIP MEMBER

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    On the stand, no load?
    Or while riding, pulling the load?

    Throttle position? (Cracked, 1/8, 1/4, 1/2)
     
  5. kommando

    kommando Well-Known Member

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    If you timed it at 5000 then it got there with no load, is the problem only there under load ie riding on the road.
     
  6. pierodn

    pierodn Well-Known Member

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    Hi.
    Ehile riding.
    Piero
     
  7. pierodn

    pierodn Well-Known Member

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  8. pierodn

    pierodn Well-Known Member

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    Hi.
    Dorry but i cannot able to understand because i am lost in translation.
    Piero
     
  9. oldmikew

    oldmikew Well-Known Member

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    could be flooding ie float needles the brass thing with the viton rubber tip - examine under magnifying glass to makesure there are no ridges on the rubber tip.. ps use google translate on posts you do not get
     
  10. pierodn

    pierodn Well-Known Member

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    Hi.
    The problem was solved.
    The left carb slider dont went up.
    Now the bike ride very well but the sparks plugs after a trip are very lean, too white and dry.
    What is the way to rich the mixture, working on the float bowls and/or on the throttle needle?.
    Timing to receck?
    Thanks.
    Piero
     
  11. Danno

    Danno Well-Known Member

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    Try raising the needles a notch. Adjusting the idle mixture may or may not be necessary depending on how it starts.

    Most running is on the slide cutaway and needle jet. I would not go to a leaner slide.
     
  12. concours

    concours Well-Known Member VIP MEMBER

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    Does it pull hard up to 3300 RPM, as expected? Or, is it lazy (down on power) all the way to 3300, the break even speed?
    Does this in 4th gear? 3rd? 2nd?
     
  13. pierodn

    pierodn Well-Known Member

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    The bike runs great, goes easily up 3300 to over, no problems anymore.
    But the spark plugs are very lean, a dry white.
    Piero
     
  14. pierodn

    pierodn Well-Known Member

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    The bike starts well.
    Piero
     
  15. 1up3down

    1up3down Well-Known Member

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    Try raising the needles a notch. Adjusting the idle mixture may or may not be necessary depending on how it starts.

    Most running is on the slide cutaway and needle jet. I would not go to a leaner slide.
    The bike starts well.
    Piero
    -------------------------------------


    Piero, the above suggestion that you raise the needles one notch will make the midrange richer and probably solve your white ish, lean spark plug condition - raising the needles does not effect starting
     
  16. Danno

    Danno Well-Known Member

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    My caveat on starting was about eliminating the primary circuit as a contributor to the problem. If it starts, runs and idles no need to fiddle with the adjustment.
     
  17. Chris Zet

    Chris Zet Well-Known Member

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    hi pierodn,

    go through all 4 (5) sequences of tuning you carburetors.....in your case i`d think that you are too lean in the load range of 1/4 to 3/4 opened throttle...this range is tuned by the needle...too lean: set the needle higher so that more gas passes through the mainjet.
    take a look at the amal-manual [on page 7 are the tuning sequences]:

    http://www.triumph3ta.nl/Downloads/Amal Concentric & Mark 2 Carburetor Technical Manual.pdf

    have a nice day, chris
     

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