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Over rev when first started.

Discussion in 'XJ Technical Chat' started by Jonathon Kent, Jun 2, 2019.

  1. Jonathon Kent

    Jonathon Kent Member

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    No, new washers were not used on the seats. Would old,washers make that much of a difference? As far as the float towers they look good pretty clean. No burs on the small pin going through the towers I can spin the pin freely from the towers and from the float. The floats have very small pin holes that do not appear to penetrate the shell of the float they actually float.. I tried with with a small bucket and gasoline to,make sure that the floats all "floated" and then slightly shook them around, I could not hear any fluid sloshing around in them.
     
  2. Jonathon Kent

    Jonathon Kent Member

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    By the way really good,idea to index the bowl instead of trying to use the caliper. Fewer things to hold in place. Is there any reason, when I refilled the rack I wouldn't get any fuel in one of the bowls when it was totally empty, and then another one would overflow?
     
  3. XJ550H

    XJ550H Well-Known Member Premium Member

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    empty bowl would happen because a float and needle keep fuel from flowing into carb bowl.
    stuck needle, stuck float, or float set incorrectly

    other options would be because screen cap on needle valve body assembly is clogged or carb is clogged at the fuel rail(tubes and tee that connect carb bodies )


    over flow
    would happen because a float and needle do not keep fuel from flowing into carb bowl.
    stuck needle, stuck float, or float set incorrectly

    other options would be crap in assembly keeping it from sealing
     
  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    just a thought on your photo of wet set you want to use a little more tubing yours is bent at quite an angle which could be compressing or restricting fuel flow into the tube .

    see photo page 8 and how long tube and routing. when I set fuel levels after the tube fills I lower tube and let it fill back to level incase the initial flow over filled the tube with an incorrect height.

    Setting the fuel levels
     
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  5. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Reusing a brass washer is usually fine, but if your carbs used the dense fiber washers (usually redish color) then they have to be replaced with new. My prefrence is to use new washers when rebuilding new-to-me carbs, since there is no way to know how often the washer has been used, and the brass will only compress so many times before it can no longer provide a seal.

    The floats are made of a plastic foam, so the pinholes are normal.
    Sounds like the floats are free to move in the carbs.
     
  6. Jonathon Kent

    Jonathon Kent Member

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    Would brand new float needles for a xj 750 work on this carburetor?
     
  7. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    Yes. the XJ650 and XJ750 have the same carbs, but with slightly different jetting.
     
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  8. Jonathon Kent

    Jonathon Kent Member

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    Awesome, i found some brand new ones on eBay. Perhaps the softer tip may help solve the flooding problem. As per your recommendation i looked and re-evaluated all posts and floats and there isn't any reason for the flooding other than the float needles. I even came across an opportunity where the carb was flooding I shook the entire thing and suddenly it stopped overflowing.
     
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  9. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    Another thing that can prevent the float valve from working is that when you tip the carbs over and back, sometimes the needle can get stuck, so just rap on the bowl a couple of times with a screwdriver handle to get it unstuck. That said, quality replacement parts are important first.
     
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  10. Jonathon Kent

    Jonathon Kent Member

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    Finally got the new needles, for the fuel inlet. Hoping to get them in on Friday, I am wondering if very small washers may help to keep the floats in perfectly straight between the towers. Any thoughts on this?
     
  11. XJ550H

    XJ550H Well-Known Member Premium Member

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    if you read the xj4ever catalog you will see they sell little washers to help keep the floats from hanging up on the float posts


    HCP18328 Aftermarket float pin tube SHIMMING WASHER, for use with all Hitachi original floats. Each stainless steel shim measures 0.0254mm thickness. Use as required or in conjunction with other size shimming washers to take up the proper amount of slop. Each:

    there are different thickness washers listed

    its not just a catalog...……..
     
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  12. Jonathon Kent

    Jonathon Kent Member

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    Thats good to know I really havent had a full opportunity to look at the xj 4ever catalog a lot.
     
  13. XJ550H

    XJ550H Well-Known Member Premium Member

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    it is a very long read
     
  14. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    I started reading it 7 years ago, and am still not done.
     
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  15. Jonathon Kent

    Jonathon Kent Member

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    Holy cow
     
  16. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    It's a good reference. Some of the information in the catalog is better than what the official shop manual provides.
     
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  17. Jonathon Kent

    Jonathon Kent Member

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    I am at my wits end.... I put the new needles in for the fuel inlet to the bowls. They are still flooding out, they are actually 19 mm for the float height. I honestly have no idea why this is happening. I really have absolutely no idea why this is happening. The floats all move freely from the posts, the needles are in good shape, they arent sticking when I put them in. Flip the carburetor over and wala they flood almost immediately. Any good recommendations for someone who can figure out whats wrong with the carbs being wet set, or aka setting the fuel height in the bowls? This problem is infuriating, I feel just about ready to walk away from the bike altogether because of this problem. Please help if possible.
     
  18. XJ550H

    XJ550H Well-Known Member Premium Member

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    float height is the starting point then you have to do an actual wet set.
    19 is to high 17 to 18 is correct

    Setting the fuel levels

    contact hogfiddles he is in your state and does carbs
     
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  19. Jonathon Kent

    Jonathon Kent Member

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    When starting off when doing the float height set, how important is it to have the carb rack tilted at an angle? Or is it not really important?
     
  20. dkavanagh

    dkavanagh Well-Known Member Premium Member

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    When wet-setting the float height (on the stand you built), the carbs should be level.
     
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