97 roadking with 80 evo sputtering

Discussion in 'Engine, Fuel and Exhaust' started by yogi, May 10, 2015.

  1. yogi

    yogi Member

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    Yesterday while riding had put in about 200 miles. I went to accelerate and my bike started sputtering on acceleration. If you run at a constant speed it runs smooth. And after a few miles it will clear up and accelerate smooth, but then a few more miles it will start sputtering on acceleration. Today i put new plugs in it and cleaned the air jet holes out. I ruled out fuel cause my wife fueled the same place as i did and hers is running fine. Any ideas on what i need to look for. Also it is showing no codes. Also lost my fuel mileage about 135 on a full tank of gas. It is showing no codes. The plugs are getting black really quik.
     
  2. SledDog

    SledDog Senior Member Staff Member Moderator

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    Check your manifold O rings and rubber bands. If they have never been changed, it's probably time.
     
  3. yogi

    yogi Member

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    If these was bad woulnt it run bad all the time? It will accelerate fine and then 5 minutes down the road it acts like its starving for fuel and then 5 more minutes runs fine again?
     
  4. Jeff Klarich

    Jeff Klarich Well-Known Member Contributor

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    What if any mods? if the new plugs are getting black that soon it doesn't sound like it's starving for gas it sounds more like to much fuel. Does it smell gassy? What color are your tail pipe tips? Lose of milage and the new plugs running black indicate to me it's running to rich.
     
  5. yogi

    yogi Member

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    no mods, it is running rich plugs are getting black quik exhaust tips are getting black and major loss of milege. the wierd thing is it comes and goes. it will run and excelerate really smooth then all the sudded run really ruff then couple minutes later smooth again. could it be the tps? has me baffled.
     
  6. Bodeen

    Bodeen Well-Known Member Staff Member Moderator Contributor

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    Carb or FI?
     
  7. yogi

    yogi Member

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    sorry mm fuel injected

    Ive checked all connections everything loks good there. Would a tps cause bad fuel mileage or shouyld i be thinking more on the lines of plug wires?
     
    Last edited by a moderator: May 11, 2015
  8. tourbox

    tourbox Senior Member

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    I don't think the MM FI had a TPS. It was cable operated for the butterflys in the unit. There was an old thread about someone having trouble with their MM that turn out to be a cracked/broken throttle plate shaft if I remember correctly. As others have stated I would check for intake leaks first. It sounds definitely like it's going rich for some reason.
    tourbox
     
  9. Jeff Klarich

    Jeff Klarich Well-Known Member Contributor

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    How many miles on the clock? as suggested check for air leaks at intake. You may also want to do a compression check if you have tons of miles.
     
  10. stray dog

    stray dog Junior Member

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    The MM does have TPS, I wouldn't have know either except I've just read about it not long ago.

    See #15
    http://images.imagessite.com/OEM_IMAGES/hd_mc_images/HD01FLHTC009.gif

    Testing
    Harley Davidson Forums

    Maybe the TPS.
    Could this be a fuel regulator problem? Can they go bad?