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Smoke, backfire, fouled plugs

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    Smoke, backfire, fouled plugs

    I'm on vacation & wife and kid left town. I finally have time, a garage, and adequate weather to tear into my 79 GS750.

    In the middle of a couple hundred mile trip, right after an expensive valve job and carb rebuild by a local shop. It was running great for a couple months last summer. Mostly just zipping around the city. Ran it straight down the highway a hundred or so miles and the problems started with it dying as soon as I let off the gas and pulled in the clutch at the exit ramp.

    I started it up last week with some starter fluid and it idled fine for about 10 minutes and then it made it around the block a few times without any noticeable problem.

    Now,

    Smoke coming out of left exhaust, white with a slight blue/grey tint.

    Dies at idle.

    Lacks power.

    Can't rev very high, struggles past 4k.

    surges and sputters.

    backfires.

    Oily plugs on center cylinders (Could it be fuel?). Sooty plugs on outer cylinders.

    Far right float is leaking gas like crazy. I think it's the float bowl gasket.

    After about 15 minutes, it doesn't want to run anymore unless I'm giving it nice steady throttle at about 3k.



    Obviously, I'm going to start with the carbs, already torn off. I'm worried about the smoke and oily plugs though. Can the carbs be the cure for all or do you think I have some bad valves or rings???? Which is more likely?
    Last edited by Guest; 03-17-2009, 01:01 AM.

    #2
    Did you replace the petcock?
    1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
    1985 GS1150ES stock with 85 Red E bodywork.

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      #3
      Originally posted by chef1366 View Post
      Did you replace the petcock?
      Yes I did, and I haven't rode it much since...

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        #4
        From the symptoms you describe it sounds like your bike is possessed by a Harley-Davidson! Dar

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          #5
          clean carbs= no sticky float

          I had the same problem with the float sticking and me leaving a hansel and grettle flammable trail back to the fuel pump. Once i cleaned the carbs the problem stopped. Not sure about your exhaust idle problems, but chances are the dirty carbs might have a thing to do with it. Good luck!

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            #6
            have you checked the coil voltage ? weak spark.. I had problems with my 79GS850 backfiring, quit running due to bad coils

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