F650 funduro 1994 cutting out issue

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Thread: F650 funduro 1994 cutting out issue

  1. #1
    Join Date
    Jul 2020
    Posts
    1
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    Default F650 funduro 1994 cutting out issue

    Hi everyone, new member here 👋
    I have been restoring my fathers funduro that was locked away off the road for the past 10 plus years. It was in quite a state having been put away after a winter ride without cleaning but have pretty much got it back to its former glory. I was hoping to ride it round to his house for his birthday after not seeing it for a long time but I am having a very frustrating final issue with it cutting out at idle. I have read the excellent threads on the common issues with these but I still cannot get to the bottom of it. Hoping the collective knowledge may point me in a new direction to resolve this last issue.
    Things I have done / tested so far since getting as it was a non starter that may help eliminate:
    Stripped and rebuilt carbs including diaphragms, cleaned little gauze filter replaced jets gaskets etc
    Oil and air filter
    Plugs
    New ngk caps as the old ones were perished and one was giving a nil reading
    New Choke cable
    Inlet manifold rubbers
    New fuel line
    Tested voltage regulator seems within range at 14 odd volts
    Idle screws at the recommended 3.5 turns
    I have stripped the carb more times than I care to admit thinking this was the issue but now I am not so sure ?

    Any help massively appreciated

  2. #2
    Join Date
    Aug 2003
    Location
    NE Lincolnshire
    Posts
    309
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    Default

    Three things needed; air, fuel and heat. Air and fuel need to be in the correct ratio. As you've changed the plug caps, I assume "heat" is supplied. Assume the bike is running OK off idle? If you set the idle speed higher than recommended, does the problem still occur? If OK that narrows down a few possible issues;

    Fuel; Float heights, blocked jet \ idle bypass passage, choke plunger sticking, water contamination, needle wear \ setting, (assume you replaced all O-Rings, not just on the jets). De-gum using a carb cleaner? Compressed air is really essential, even if you get it from an aerosol can rather than a compressor.

    Ignition; multi-pin blocks, coil voltage, CDI unit voltage and connectors. A Gunson Colortune can help to eliminate some guesswork. Iridium spark plugs help idling

    Air; valve clearance \ operation, double-check induction \ air filter rubberware \ alignment and thightness. I prefer to get the carbs out the "proper" way rather than levering them out between the rubberware.

    A bit more to chew on..... Frustrating, more so given carbs are such a PITA to access \ work on

  3. #3
    Bike
    F650(1997) & F650GS(2000)
    Join Date
    Aug 2004
    Location
    Bedford.
    Posts
    828
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    Default

    Set main idle screw to get an idle speed --- adjust each air idle screws to get best rpm rise. then back off idle screw.


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