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How to lean out carbs?

Discussion in 'XJ Technical Chat' started by tinwakr123, Oct 14, 2007.

  1. tinwakr123

    tinwakr123 Member

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    Hi Everyone,

    I think the carbs on my bike are set a tad rich, could someone direct me in leaning them out a bit? I am experiencing what I believe to be flooding when starting in the morning on a cool day. I still need to check the petcock to make sure it isn't leaking though. Any ideas as to how I can tell for sure that the petcock is/isn't leaking other than taking it apart?

    Thanks,
    Chuck
     
  2. Captainkirk

    Captainkirk Member

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    If the petcock was leaking, your carbs wouldn't be running rich or flooding....they would behave as normal. A bad petcock would cause either external leakage or fuel starvation. I rigged up a remote tank for adjusting carbs that bypasses the tank and petcock completely-constructed from PVC pipe. If you're interested I can zip you some pix. Very easy to construct and extremely useful for carb synching.
    Back to the question....your problem could be caused by high float height. Your manual should have a procedure for checking it, If not, PM me. I have a Maxim X shop manual out in the shop.
     
  3. BlueMaxim

    BlueMaxim Active Member

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    This is correct as long as the float valves are known to be working. If they are leaking the fuel level will be high and the carbs flooding which leads to fuel in the crankcase. Easiest and best way to check the petcock is to remove the fuel line with teh engine off and with the petcock set to "ON" or "RES". If fuel flows in these positions then the petcock is leaking. Fuel should only flow with the petcock in the "PRI" position if the engine is off. With the engine running fuel will flow in any position.
     
  4. rpgoerlich

    rpgoerlich Member

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    If the diaphrams in the petcock has a hole in it, you could draw fuel into the intake through the vacum line.

    Check your plugs and see which carb is the culprit.
     
  5. RickCoMatic

    RickCoMatic Well-Known Member

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    You adjust the Mixture by turning IN or OUT the Pilot Mixture Screws on the top, front of the Carbs.
    Each Carb has a Pilot Mixture Screw (Sometimes hidden beneath an Anti-tamper Plug) ... just to the side of the Pillar Support for the Enrichment Valve Operating Rod.

    These Screws are SOFT. You need a screwdriver which fits the slot with such precision that there is zero end-play, otherwise you risk damaging the top of the Screw (which are often "Stuck") and will require a high level of turning torgue to move it.

    Prepare it site and the Screw before turning it.
    Clean the hole out with Carb Cleaner
    Oil the hole and apply heat if the Carbs are being cleaned on-the-bench.

    The Factory Preset is 2-1/2 Turns OUT from the Bottom
    Research provided by a vast number of Members of this Forum indicate the Ideal setting to be 3.0 (or more) out for best performance.

    Read your Plugs.
    If they a Black or a Deep, deep Brown --- you can "Lean-out" the Mixture.

    Turn the Pilot Mixture Screws IN -- 2 Degrees -- (About the width of a Nickel) -- to lower the Volume of the Pilot Fuel introduced to the Combustion Chambers for Idle and Off-idle sustaining mixture to the Intake.

    Make notes concerning your adjustments.
    (Individual Cylinders may need more than 2-Degrees adjustment -- depending on the Individual Cylinders Plug Read.)
     

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