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sputter at high speed

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    sputter at high speed

    I have a problem with my '82 GS650L sputtering at much above 5000 rpm in any gear. It dies for a beat or two, then catches, then sputters, and so on, the upshot being it's not a smooth ride at highway speed, and hard to go much more than that.

    Here's what has been done and is known:
    1 - Bike starts well and idles very smoothly.
    2 -Around town at low throttle openings, also runs very well.
    3 - Carbs have been completely taken apart, dipped in cleaner, blown out, new O-rings and needles/seats installed.
    4 - Floats float, and have been set at the correct height, on the lower upside down height/more fuel side to prevent starvation. Thought that might have been the solution, but it wasn't.
    5 - Petcock rebuilt, flow seems good, sputters continue even on "PRIME" position so doesn't seem to be vacuum related.
    6- Valves adjusted to specs.
    7 - New carb boot O-rings installed, boots appear to be sound.

    Now here's what I'm hoping is a clue: I hooked up an old inductive tune-up meter I have lying around, the kind that clips over the spark plug wire to sense rpm via spark impulses. Every now and then, on any plug wire, the tach reading dips to zero, then back up to a reading.

    Does this indicate the plug wires are defective? They are the originals, so not surprising if they are perished. Just hoping that is not a false trail to a solution.

    #2
    Until someone more knowledgeable respond.

    I had a similar problem where above 5k rpm it starts sputtering/staggering but below that is fine (rpm does not rise suddenly - so not clutch related for me). Had the carbs appart a number of times too, which didn't help But what fix it for me was working on the points, I sanded down the points and one of the screws for the condensers was loose, so tighten it. Dynamic timed it and it was gone:-D I have ordered Dyna S ignition so I don't have to worry about the points/condenser anymore\\/

    Hope it helps. Good luck!

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      #3
      electronic

      this one has electronic ignition already

      Comment


        #4
        Since it happens on all plugs, I'm guessing your igniter is starting to fail. For now, the problem is intermittent. When the unit fails altogether, you'll know it, of course. If you can get your hands on a spare igniter for testing purposes, you can check my idea out.

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