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  • Engine Bogs and Stalls in Gear

    I started my 1979 XS1100SF yesterday after I washed it.

    It started normally, ran on the enrichers normally, then idled down normally after it warmed up.

    When I put it into into gear, there was a bigger-than-normal clunk and the engine abruptly died.

    I found if I gave it some throttle, I could get it to run in gear with the clutch pulled in, but when the idle was in the 1000-1200 RPM range, there was a mechanical ka-dunk, ka-dunk, ka-dunk sound from the lower part of the engine.

    I found I could easily roll the bike around with the clutch lever pulled in and the engine running in gear. Therefore the clutch seems normal, and everything downstream of the clutch seems normal.

    I rode the bike gently for about a mile it felt like the bike had less power than normal , but it shifted through the gears normally. Whenever I slowed, the engine wanted to die unless I gave some throttle. It ran normally whenever I put it in neutral.

    It seems like part of the transmission is not turning easily when I put the bike in gear with the clutch lever pulled.in.

    I have to start thinking what is turning when the bike is in gear vs when it is not in gear? Something between the engine and the clutch?

    I did a lot of work on the bike over the winter, including new wheel bearing, new steering bearings, new tires, new shocks, etc. The only thing that might be related is that I adjusted the OEM cam chain tensioner. I guess I can start by re-adjusting the CCT just in case it might be related....but it doesn't seem like it would be.

    I read through old threads and found one rare similarity. It has happened that the neutral switch wire can short the ign pick-up coil wires inside the harness. I think that is worth checking. Maybe I can pull the wire off the neutral switch and see how it behaves.

    Meanwhile, I need your thoughts.









    -Mike
    _________
    '79 XS1100SF 20k miles
    '80 XS1100SG 44k miles
    '81 XS1100H Venturer 35k miles
    '79 XS750SF 17k miles
    '85 Honda V65 Magna ~7k miles
    '84 Honda V65 Magna 48k miles (parts bike)
    '86 Yamaha VMAX 9k miles

    Previous: '68 Motoguzzi 600cc + '79 XS750SF 22k miles +'84 Honda V65

  • #2
    Wiring harness probably got wet washing the bike, I would let it dry out some and see if it runs better.
    If it runs fine in neutral, that is more than likely the problem. The water can cause 2 cylinders to drop out.
    Last edited by bikerphil; 05-06-2022, 08:57 AM.
    2H7 (79)
    3H3

    "If it ain't broke, modify it"

    Comment


    • #3
      I agree, my '79SF does NOT like showers...
      Ray Matteis
      KE6NHG
      XS1100 E '78 (winter project)
      XS1100 SF Bob Jones worked on it!

      Comment


      • #4
        I'm thinking timing advance got wet. Check the wires for internal breaks
        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.

        Comment


        • #5
          I got caught in a sudden downpour years ago when I was out riding with childhood friends. Bike ran like crap before things dried out. Friends Harley who had the Screaming Eagle air filter setup not so much, that hated the rain. I carry wire drier available in auto parts stores.
          1980 XS1100 SG
          Inline fuel filters
          New wires in old coils-outer spark plugs
          160 mph speedometer mod
          Kerker Exhaust
          xschop K & N air filter setup
          Dynojet Recalibration kit
          1999 Kawasaki ZRX1100
          1997 Jeep Cherokee 4.5"lift installed

          Comment


          • #6
            Thanks for the input.

            It seems you are all correct.

            I thought about it and decided the neutral switch wiring was the best explanation.

            So went out today to play with it, and everything was fine!

            Since the problem only happened when I put it into gear, we can be sure that the water enhanced a short between the neutral switch and the pick-up coil wires for 2 of the cylinders.

            I've never had it happen before on this bike, and I have rode this bike in the rain once or twice with no issue.

            I guess I'll let it go for now and keep an eye on it.

            Happy days again!
            -Mike
            _________
            '79 XS1100SF 20k miles
            '80 XS1100SG 44k miles
            '81 XS1100H Venturer 35k miles
            '79 XS750SF 17k miles
            '85 Honda V65 Magna ~7k miles
            '84 Honda V65 Magna 48k miles (parts bike)
            '86 Yamaha VMAX 9k miles

            Previous: '68 Motoguzzi 600cc + '79 XS750SF 22k miles +'84 Honda V65

            Comment


            • #7
              A few of us have agreed that water splashes up in the location of the connector for the P/U coils behind the fuse panel. Wrapping the connector with electrical tape may help with this problem.
              2H7 (79)
              3H3

              "If it ain't broke, modify it"

              Comment


              • #8
                Originally posted by Radioguylogs View Post
                Thanks for the input.

                It seems you are all correct.

                I thought about it and decided the neutral switch wiring was the best explanation.

                So went out today to play with it, and everything was fine!

                Since the problem only happened when I put it into gear, we can be sure that the water enhanced a short between the neutral switch and the pick-up coil wires for 2 of the cylinders.

                I've never had it happen before on this bike, and I have rode this bike in the rain once or twice with no issue.

                I guess I'll let it go for now and keep an eye on it.

                Happy days again!
                You might also want to put a light coat of dielectric grease in your spark plug caps. Water up in them can also cause the problems you experienced.
                2 - 80 LGs bought one new
                81 LH
                02 FXSTB Nighttrain
                22 FLTRK Road Glide Limited
                Jim

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