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  • Miss In Engine

    My '78 XS1100 has got me perplexed. I've only got a couple hours run time on it since it was resurrected after sitting for about 10 years. At first it ran great (most of the time), then it started not firing on #4. The pipe was only warm. I could pull the plug wire off and put a spare plug in it and it was firing. I thought maybe the valves were sticking. Then the next time I took it out, #4 was firing, but #1 wasn't. Now #1 & 4 are firing, but #2 & 3 aren't. However, I can put a spare plug in #2 wire and the spare plug fires great. Any ideas?

  • #2
    First thing I would try is unscrewing each spark plug cap and cut 1/4 inch of wire off, then screw the caps back on and try it again. Corrosion forms at the ends and can give you a weak or no spark. HTH
    2H7 (79) owned since '89
    3H3 owned since '06

    "If it ain't broke, modify it"

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    • #3
      As eratic as this sounds, I'm with Phil. I think you have one or more corroded connections in your ignition circuit. Also do not overlook that old glass tube fuse box if you still use it.
      Life is what happens while your planning everything else!

      When your work speaks for itself, don't interrupt.

      81 XS1100 Special - Humpty Dumpty
      80 XS1100 Special - Project Resurrection


      Previously owned
      93 GSX600F
      80 XS1100 Special - Ruby
      81 XS1100 Special
      81 CB750 C
      80 CB750 C
      78 XS750

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      • #4
        I am going with the plug wires too. Does the bike still have the original coils? If so try the new wires in old coils fix then it just eliminates the possible problem of 30 year old wires. You can find that fix here http://www.xs11.com/forum/showthread.php?t=137
        Nathan
        KD9ARL

        μολὼν λαβέ

        1978 XS1100E
        K&N Filter
        #45 pilot Jet, #137.5 Main Jet
        OEM Exhaust
        ATK Fork Brace
        LED Dash lights
        Ammeter, Oil Pressure, Oil Temp, and Volt Meters

        Green Monster Coils
        SS Brake Lines
        Vision 550 Auto Tensioner

        In any moment of decision the best thing you can do is the right thing, the next best thing is the wrong thing, and the worst thing you can do is nothing.

        Theodore Roosevelt

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        • #5
          I had a similar problem with mine after i replaced
          my engine with a spare that had been sitting for a few
          years, mine was doing it on cylinders 1 or 4, if the engine
          is burning oil be careful not to have the carbs running rich
          it will cause the plugs to foul.
          there was a few times i had to ride it home holding the spark lead just of
          the spark plug to get the cylinder to fire.
          pete


          new owner of
          08 gen2 hayabusa


          former owner
          1981 xs1100 RH (aus) (5N5)
          zrx carbs
          18mm float height
          145 main jets
          38 pilots
          slide needle shimmed .5mm washer
          fitted with v/stax and uni pod filters

          [url]http://www.youtube.com/watch?v=3pA8dwxmAVA&feature=mfu_in_order&list=UL[/url]

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          • #6
            Have you pulled the plugs? They could be dead or carboned up. I had my bike running way too rich... when I put in fresh plugs, it would run great for about a half hour, then it would idle really crappy. I'd pull the plugs, clean them, and it would run fine for another half hour.

            The reason I was having this trouble was because I had replaced my idle mixture screws, and I put them in way too rich. Each time I pulled the plugs to clean/inspect them, I tightened the mixture screws. I eventually got help from another member with a Colortune, and got them adjusted much better.

            Good luck!
            '80 SG with motor from a '82 XJ

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