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  • #1

    Random Stumbles

    This is my third season with this bike and have had absolutely no issues with it. A couple of weeks ago it started to randomly stumble. This can happen at low speed or high speed. On one occasion it actually paused and backfired twice before resuming normally. Very annoying at highway speed. I'm having a hard time correlating the stumbles with any particular event. Sometimes it stumbles when I accelerate after a deceleration. Sometimes it seems to happen after I've gone over a bump which could be the decel / accel again I guess. Sometimes it just happens as I'm rolling along smooth pavement at a steady speed. Maybe I'm getting paranoid about this now but the bike sometimes feels to me like I'm riding into a strong headwind even when there is no wind, like it's stumbling almost imperceptibly all the time.

    I replaced the plugs. No difference. I removed the coils and found one with a crack in it and said 'Ah Hah!' Ordered a set of NOS coils and installed, still same problem. I dismantled everything, cleaned and reset every connector I could find. Still stumbles.

    I removed the carbs thinking maybe I had a problem with fuel delivery. Everything looks super in there. Float heights are perfect. Gave them a good cleaning while I had them off. The bike has been running a bit rich so I tweaked the idle jets while I was at it then re-installed the carbs. The problem is still there. No better, no worse.

    I checked the pickup coil and wiring. Don't see anything wrong there. Opened up the TCI box for a look. Nothing burned or obviously wrong there.

    Don't know what else to do. I'm at the end of my rope. Anyone with any ideas?

    Greg
    '81 XS1100 H
    Special Tank
    Special Headlight
    Tags: None
  • #2
    You say you cleaned the carbs, but how thoroughly? Did you pull the needles AND the seats? Did you pull out the emulsion tubes and the pilot jets? Have you sync'd the carbs lately? You'd be amazed at how much difference a carb sync will make.
    1980 XS850SG - Sold
    1981 XS1100LH Midnight Special (Sold) - purchased 9/29/08
    Fully Vetterized and Dynojet Kit added, Heated Grips, Truck-Lite LED headlight, Accel Coils, Irridium plugs, TKAT Fork Brace, XS850LH Final Drive & Black SS Brake lines from Chacal.
    Here's my web page devoted to my bike! XS/XJ User's Manuals there, and the XJ1100 Service Manual and both XS1100 Service manuals (free download!).

    Whether you think you can, or you think you cannot - You're right.
    -H. Ford

    Comment

    • #3
      Ok, you said you "looked" at the pickup coil wiring. Did you check the pickup coil resistance and tug the wires while doing so? It sounds like it could be pickup coil issues to me. I have not had those issues myself (knock on wood) but many have, and everything but the XJ's can get the problems as they ALL have the vacuum advance which is the ONLY thing in the timing system that makes the wires flex when it operates. Make sure you try to stretch them, but don't pull too hard as they ARE fragile and pulling too hard can make good wires bad. But if they will stretch, they are likely the problem, and if you pull them and move them around while it's idling if they are bad it will likely show up then.
      Cy

      1980 XS1100G (Brutus) w/81H Engine
      Duplicolor Mirage Paint Job (Purple/Green)
      Vetter Windjammer IV
      Vetter hard bags & Trunk
      OEM Luggage Rack
      Jardine Spaghetti 4-2 exhaust system
      Spade Fuse Box
      Turn Signal Auto Cancel Mod
      750 FD Mod
      TC Spin on Oil Filter Adapter (temp removed)
      XJ1100 Front Footpegs
      XJ1100 Shocks

      I was always taught to respect my elders, but it keeps getting harder to find one.

      Comment

      • #4
        +1 on pickup coil wires.
        2H7 (79) owned since '89
        3H3 owned since '06

        "If it ain't broke, modify it"

        ☮

        Comment

        • #5
          +2 on the pick-up coil wires. Give them a pretty good tug, and watch especially where they are retained by a crimp fitting just before they leave the case. Open the crimp when you do this, then squeeze it back after you're done.
          Ken Talbot

          Comment

          • #6
            +3 on the pick up coil wires. Could not have more accurately described my probs with them if you were here when it happened.
            2-79 XS1100 SF
            2-78 XS1100 E Best bike Ever
            80 XS 1100 SG Big bore kit but not fully running yet.
            Couple of more parts bikes of which 2 more will live!

            Comment

            • #7
              Broken Pickup Wires

              You guys are right on the money. Three of the four pickup wires just inside the little clip are stretchy, like the wire is broken inside them. I don't know how the bike worked at all. Found your tutorial here on fixing this Ken. THANKS guys for the great advice. You guys have got a place to crash if you ever come out to the east coast of Canada for a run.

              Greg
              Last edited by gixxer; 09-01-2010, 03:46 PM.
              '81 XS1100 H
              Special Tank
              Special Headlight

              Comment

              • #8
                Guys, I know that's my issue. Been trying to find the short; off and on; for 60 days. I need the specifics on how to check the resistance. Perforate the insulation? Is there a logical starting point and ending point.
                Forgive my ignorance, but I don't want to make it worse than it is. Maybe I need a picture. It's not in the manual's where to position the mutimeter.
                The wire is certainly very soft and flexible and I don't want to mess something else up.
                '81 XS11 LH (MNS)

                "On a scale of 1 to 10, I have an eleven!"

                "Excess is easier to say than XS,"

                Comment

                • #9
                  Originally posted by FANNING507 View Post
                  Guys, I know that's my issue. Been trying to find the short; off and on; for 60 days. I need the specifics on how to check the resistance. Perforate the insulation? Is there a logical starting point and ending point.
                  Forgive my ignorance, but I don't want to make it worse than it is. Maybe I need a picture. It's not in the manual's where to position the mutimeter.
                  The wire is certainly very soft and flexible and I don't want to mess something else up.
                  It's not about checking resistance. You take the timing cover off, and pull on the wires. If the metal strands inside the insulation allow the insulation to stretch, you know they are broken, and need to be fixed. A nice firm tug should be good, since you might still have a few strands of the wire left, but not enough to make good contact. The firm tug should brake the last few strands if they are weak enough to have been causing the problem.
                  1980 XS850SG - Sold
                  1981 XS1100LH Midnight Special (Sold) - purchased 9/29/08
                  Fully Vetterized and Dynojet Kit added, Heated Grips, Truck-Lite LED headlight, Accel Coils, Irridium plugs, TKAT Fork Brace, XS850LH Final Drive & Black SS Brake lines from Chacal.
                  Here's my web page devoted to my bike! XS/XJ User's Manuals there, and the XJ1100 Service Manual and both XS1100 Service manuals (free download!).

                  Whether you think you can, or you think you cannot - You're right.
                  -H. Ford

                  Comment

                  • #10
                    Originally posted by FANNING507 View Post
                    Guys, I know that's my issue. Been trying to find the short; off and on; for 60 days. I need the specifics on how to check the resistance. Perforate the insulation? Is there a logical starting point and ending point.
                    Forgive my ignorance, but I don't want to make it worse than it is. Maybe I need a picture. It's not in the manual's where to position the mutimeter.
                    The wire is certainly very soft and flexible and I don't want to mess something else up.
                    Here is the link to the pickup coil fix Hanning http://www.xs11.com/forum/showthread.php?t=543
                    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

                    Comment

                    • #11
                      Whoa!

                      Fixed my three pickup wires (http://www.xs11.com/forum/showthread.php?t=543) and took ol' Betsy out for a run. I know now that the vacuum advance has NEVER worked on this bike since I got it. I was happy with the power it had before but now, it's SCARY! Smooth as silk at all speeds, not a single stumble. It's even smoother during shifts because the revs are not dropping so quickly and it's riding better because the engine isn't stumbling when I hit a bump.

                      I feel like I just got a new bike, thanks guys!
                      '81 XS1100 H
                      Special Tank
                      Special Headlight

                      Comment

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