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#4 cyl running rich on a 16v 750.

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    #1

    #4 cyl running rich on a 16v 750.

    My 84 "katana" 16 valve GSX750 continues to soot up on the #4 cylinder. 1,2 & 3 are fine. Have replaced the intake 'O' rings, synced the carbs with the gauges, set the pilot screws at 2 and a bit on all. The carb boots are fine and doesn't appear to be sucking in air when do the old RP7/WD40 spray on it when running. Carbs were removed and done 1000k's ago. Am I looking at a float level prob on #4 causing this? I get about 3-400K's before it starts mucking up like this, then the bike just misses on that cylinder. It's becoming annoying now, anybody got any thoughts on it?

    Hoges.
    Tags: None
    #2
    Possibly the #4 has a bad spark plug cap or wire and is getting a weak spark.
    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.

    Comment

      #3
      Originally posted by chef1366 View Post
      Possibly the #4 has a bad spark plug cap or wire and is getting a weak spark.
      Agreed, but it could be a bad oil seal on the valve stem.

      Can you post up a picture of your plugs?
      1978 GS 1000 (since new)
      1979 GS 1000 (The Fridge, superbike replica project)
      1978 GS 1000 (parts)
      1981 GS 850 (anyone want a project?)
      1981 GPZ 550 (backroad screamer)
      1970 450 Mk IIID (THUMP!)
      2007 DRz 400S
      1999 ATK 490ES
      1994 DR 350SES

      Comment

        #4
        Hi,

        Did you try a new plug cap? Did you snip off 1/8" to 1/4" of the spark plug wire and attach the plug cap to fresh, uncorroded wire? Are you sure that #4 carb is really, really clean and properly adjusted? Hmmmm, curious.


        Thank you for your indulgence,

        BassCliff

        Comment

          #5
          Great idea on the spark plug cap and wire. I actually didn't think of that for a potential cause. I was starting to look at the choke butterfly staying on partially. Will have a look and remove the cap and cut off some cable and re-attach. The carbs may well need to come off again as I have clocked up 3000K's since last cleaned up. Thanks fellas and will let you know.

          Comment

            #6
            Okay, just had a quick look whilst at work at the offending #4 spark plug cap, and seperated the plug cap from the cable. Very very green looking copper wire appeared, plus the screw inside the cap was pretty ordinary as well. I'll ride her home tonight and start cutting the cable back until I find a bit of nice shiny copper wire! Might be time to check the others maybe. Will report on the outcome.

            Comment

              #7
              Not too many of us 16 valve 750's on here....

              I'll be interested to hear how it turns out as I have the same model.
              BTW, know where I can get some replacement mirrors at a reasonable price?

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