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Syncing troubles

Discussion in 'XJ Technical Chat' started by splazoid, Mar 23, 2012.

  1. splazoid

    splazoid Member

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    I cannot seem to get the carbs to sync fully - 1,2, and 3 are all at about four PSI, while 4 is at three. Turning the sync screw between 3 and 4 will only lower 4's vacuum, not raise it any further. I'm using a 4 vacuum gauge carburetor synchronizer.

    It rides pretty smoothly once at speed, but under medium to high load while accelerating around 30MPH, it chugs a bit and loses some power, but if I slowly accelerate, it's really zippy at 50+.

    Should I switch to color tuning now because they're close, or is 1 PSI enough to mess with tuning?

    Here is what I have done thus far:

    Blocked YICS with a YICS eliminator, fresh o-rings.

    Started out with bench-synced carbs, minor changes to this point.

    Mixture screws at the starting 2 1/2 turns out.

    Switched 4 to a different vacuum gauge to see if one of the gauges is inaccurate, same readings.

    I have recently replaced throttle shaft seals, float valves and orings, float bowl gaskets, drain screw orings, idle mixture orings, fuel rail orings, confirmed correctly sized jets. Also recently returned to stock mufflers, this required replacement of head to header gaskets.

    Set float levels with clear tubing using fuel.

    And of course, triple-checked valve clearances, glad i did, one was still out on the final check.
     
  2. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    The YICS "eliminator" tool (the one that's only 3 o-rings and spacers) doesn't work properly if at all.

    You could be fighting with trying to sync with a partially blocked YICS system.

    MPH means nothing; these are 6-speed bikes. If you want to discuss rideability issues, it helps to know what RPM you're talking about. For instance, there's no way you're all the way in 6th at 30mph, so what is the RPM of the "bogginess?"

    Are you running with any intake mods?

    IF IT WERE ME:

    I'd properly block the YICS, set the mixture screws at 3 turns out, and re-sync.

    Then do the ColorTuning; and then re-check the sync.

    Then REMOVE the YICS tool.
     
  3. splazoid

    splazoid Member

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    Thanks for the reply as always, fitz.

    The eliminator has 6 o-rings, two between each carb (none on either end).
    [​IMG]
    Comparing the sync readings with vs without the eliminator, there was a definite difference.

    The riding issues I was talking about were in 3rd gear, about 30 MPH, then taking up from 3k up to 4.5-5K. Instead of it shooting off like these bikes are able, it performed poorly as mentioned, but rode smoothly if i crept up to 5-6k RPM.

    I'll try to block the yics a bit better, set them to 3 turns out, and see what we get tomorrow.
     
  4. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    That's the tool I was talking about that doesn't work.

    Get a real one from Len, or use a long strip of an old (100% cotton) t-shirt soaked in oil and twisted into a rope.

    And be sure there aren't melted remnants of that tool left in the passages.
     

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