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Number 3 cylinder kaput

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  • #1

    Number 3 cylinder kaput

    My 79 runs very rich, I noticed that number 3 cylinder exhaust pipe is cold.
    I have spark and compression on that cylinder.

    I am assuming that number 3 carb. is faulty. Jets plugged, Float needle valve
    stuck closed etc.

    Any other ideas?
    78E, 79F, 80G
    Tags: None
  • #2
    Spark, compression, and proper air/fuel mixture. Two of the most important are checked-out. So, that leaves what you've already stated. #3 carb. Greg's favorite carb. I'd pulled the rack and clean the vent tubes, inlet tubes, then work your way into the carb. Since you did not mention gas in your air filter, I'd count-out a stuck float. Blow that sucker out and cross your fingers that she turns-over. Just for shiggles, you should swap 2&3 plug leads and see if anything changes.
    1979 XS1100F
    2H9 Mod, Truck-Lite LED Headlight, TECHNA-FIT S/S Brake Lines, Rear Air Shocks, TKAT Fork Brace, Dyna DC-I Coils, TC Fuse Block, Barnett HD Clutch Springs, Superbike Handlebars, V-Star 650 ACCT, NGK Irridium Plugs, OEM Exhaust. CNC-Cut 2nd Gear Dogs; Ported/Milled Head; Modded Airbox: 8x8 Wix Panel Filter; #137.5 Main Jet, Viper Yellow Paint, Michelin Pilot Activ F/R, Interstate AGM Battery, 14MM MC, Maier Fairing, Cree LED Fog Lights.

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    • #3
      #3 has evil demons in it.

      Is it just missing at idle or all the time? If it's just at idle you could have a broken idle mixture screw with a tip stuck in the idle orifice or maybe a plugged cross over port from the pilot well to the main well.

      If it's missing above idle you might have a bad spark plug or, as has been stated, a plugged fuel inlet port.

      Take the plug out of the bottom of the #3 float bowl and see if there is fuel in it.

      Just a couple things I've run into before.
      Greg

      Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.”

      ― Albert Einstein

      80 SG Ol' Okie;79 engine & carbs w/pods, 45 pilots, 140 mains, Custom Mac 4 into 2 exhaust, ACCT,XS850 final drive,110/90/19 front tire,TKat fork brace, XS750 140 MPH speedometer, Vetter IV fairing, aftermarket hard bags and trunk, LG high back seat, XJ rear shocks.

      The list changes.

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      • #4
        Number 3 Kaput

        No it is cold all the time.
        Ill drain the bowl and see it it has gas.
        78E, 79F, 80G

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        • #5
          Clean the plug, and retry.
          Skids (Sid Hansen)

          Down to one 1978 E. Stock air box with K&N filter, 81H pipes and carbs, 8500 feet elevation.

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          • #6
            Me too, Now hitting on all 4

            Originally posted by skids View Post
            Clean the plug, and retry.
            My #3 also gave trouble several days ago. Found slight gas leak, then fuel under connection to air box and in air box. I used Yamalube carb dip, drained #3 carb bowl, put cleaner in fuel line above carb, turned engine over several times, left it sit several hours, charged battery, drained all bowls, fresh gasoline added, Started and rode bike. No fuel leaks , but #3 exhaust pipe cold.

            Cleaned plug (it was black, wet & oily looking). retry...and

            YEE HAW!! hitting on all 4. I have ridden it every day since, (some days several outings).

            Good luck wrenching.
            It is a great big beautiful world out there
            Brent in GA
            Yamaha 80XS1100SG, HD Firefighter Special Edition 02 Road King, Honda 450 rat, 08 Buell 1125R tour modified, 83 goldwing parts bike gone-traded for XJ1100, 2014 HD electraglide police

            Comment

            • #7
              Yeah, all of my bad bike juju has originated in Old Number Three. Must be an unlucky number in Japan.
              "Time is the greatest teacher; unfortunately, it kills all of its students."

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