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URGENT Carb Tuning Help Needed....

Discussion in 'XJ Technical Chat' started by Alive, Apr 13, 2007.

  1. Alive

    Alive Active Member

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    So the carbs on my 900 were stripped down recently and I replaced the float valves, and put a 105 main jet in them (up from a 102.5).

    I carefully set the float level in each carb to between 1-3mm from the carb housing and threw them back on... Now it's running really rough.

    Runs fine when it's cold but feels like it's almost flooding when its warm. The mixture screws are all 3 1/2 turns out.


    I read somewhere that running good cold and bad when hot points to a specific problem but I cannot find the original thread it was posted in and cannot remember what the fix was for it...

    The carbs were synced recently (close enough for it to run)...

    I really want to go for a decent ride in a couple of hours so any help would be appreciated

    Oh and I don't have a colourtune or sync tool :(

    Thanks
     
    Alive, Apr 13, 2007
    #1
  2. KiwiXJ750D

    KiwiXJ750D Member

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    Sync tool:

    5 metres clear tube, some 2 stroke oil, tape, broom stick.

    Method:

    tape doubled over tube to stick half fill with 2 stroke oil to about 3 feet on each side.

    Use it to do 2 pots at a time.

    Cost $4!

    Why did you go up in jet size?

    Try 3 turns out.

    Your float might be a bit high. When I did my spare set of carbs I set them as close to 3 mm as I could.

    BTW nice job on the 900, looks factory fresh!
     
    KiwiXJ750D, Apr 13, 2007
    #2
  3. Alive

    Alive Active Member

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    That's really easy ... Why didn't I think of that?? :lol:

    Went up another size for better performance with the custom mufflers and when it's cold... IT FLYS :)

    I'm going to try 3 then 4 turns out this morning....

    There's a charity bike run in Hamilton today and I really want to go
     
    Alive, Apr 13, 2007
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  4. BlueMaxim

    BlueMaxim Active Member

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    Points to a rich mixture. Turn the idle screws in about 1/2 turn. Ride then see how it runs warm. Turn in 1/4 after that until it smooths out warm.
     
    BlueMaxim, Apr 13, 2007
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  5. Alive

    Alive Active Member

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    Just looked at the book and it says the float level should be 5mm -/+ 1mm.

    Have the carbs off and i'm resetting the float level and have set the mixture to exactlu 3 turns on each....

    Blue.... Failing this, I'll be trying that

    Cheers
     
    Alive, Apr 13, 2007
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  6. Alive

    Alive Active Member

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    Finally got it sorted... Took a while to workout that I needed to re-seat the float valves before they would adjust properly... Lowered the float level and set the mixtures to exactly 3 turns and it's sweet....

    Unortunately I missed out on the ride, but nevermind.
     
    Alive, Apr 13, 2007
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