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Help Adjusting mixture and multiple bike starts.

Discussion in 'Maintenance' started by DieDemon, Aug 1, 2020.

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  1. DannoXYZ

    DannoXYZ Well-Known Member

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    Coil is most likely fine. But good practice measure it to be sure. It’ll come in handy in future to compare readings.

    Next, try this:

    1. Start bike on choke only. No starter fluid ever, it will dissolve your slide diaphragms! Use little squirt bottle and spray some petrol instead.

    2. Gradually reduce choke as RPMs increase, aim for around 2000-2500rpm. Is it able to idle on its own with no choke after fully warming up (5-10min)?

    3. Are you able blip throttle and go from 2500 to 5000rpms quickly?
     
    DannoXYZ, Aug 31, 2020
    #41
  2. DieDemon

    DieDemon Active Member Premium Member

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    Sweet as. Will give the spray bottle a go next time.

    Yup will idle til about 2000rpm no problems no choke needed when warm.

    At the current setting of 1.75 turns out on the mixture screw I have to be gentle on the throttle til about 4k rpm and then it's happy, but between 2000-4000 it backfires off the carbs. At 1.5 mixture it runs the best so far, but same problems of it won't go under 2000 rpm without dying. Can blip the throttle with no problems.

    I can retry 1.5 mixture and take a video so you can see at some point
     
    DieDemon, Sep 1, 2020
    #42
  3. ShaneP

    ShaneP Well-Known Member

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    That was not what I would have expected, have you tried turning the mixture screw in further and seeing how that goes? You confirm that the air jets and channels were clear?
     
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    ShaneP, Sep 3, 2020
    #43
  4. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Only problem with using the old Needle Jets(Emulsion tube's) is that the new Needle's will suit the new Needle Jet's, possibly not the original's
    They may not be compatible with each other, old and new.

    Also you mentioned you set the new Slide Needle's up the same way the old one's were, was that in the 3rd slot down (centre slot) ?
     
    my67xr, Sep 3, 2020
    #44
  5. DieDemon

    DieDemon Active Member Premium Member

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    I confirmed the main jet was the same as the old one because it had the size written on the side of both 97.5 and the pilot jets had their model number on them and they were the same. unfortunately the needle jets didnt have any model number on any of them and the hole difference between the new and the old ones were very different. The old jets had a much bigger hole.

    The slide needles are set to the 2nd from the top. Not quite the middle.
     
    DieDemon, Sep 3, 2020
    #45
  6. DieDemon

    DieDemon Active Member Premium Member

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    Turned the mixture screws to a 1.0 setting and it ran for a bit and died from bogging out by what I was hearing.
     
    DieDemon, Sep 3, 2020
    #46
  7. DannoXYZ

    DannoXYZ Well-Known Member

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    I agree with Simon’s last post. Trouble in 1000-2000 days rpm-range points to clogged pilot circuit. You’ll want to scrub fuel-circuit between pilot-jet and carb venturi with brushes and PEA-based fuel-system cleaner (Techron Concentrate Plus).

    Then go in reverse direction. Find bleed-hole in venturi for pilot-circuit. Bend soft copper wire of matching diameter 10mm from end to 90-degrees. Use this to gently poke and floss bleed hole. Blast out in both directions.

    Spray carb-cleaners no longer work to remove varnish due to removal of chlorinated compounds. Cleaning carbs thoroughly requires lots of mechanical scrubbing and tiny poking tools.
    Micro soda blasting all circuits also helps. Strong enough to remove varnish, but not hard enough to remove metal.
     
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    DannoXYZ, Sep 3, 2020
    #47
  8. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    Second slot down is leaner than standard, this wouldn't be helping it transition from the pilot circuit onward's
    Are you sure the new needle and the old emulsion tube are compatible ?
    If the old emulsion tube was bigger, you are now using a new needle that is smaller diameter compared to the original with it, this will give it a richer mixture as the slide start's to open
     
    my67xr, Sep 3, 2020
    #48
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