Question About Engine Dying While Riding In Rain....

Discussion in 'Technical Help' started by Johnnymoto, Nov 12, 2020.

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  1. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    It happened twice already. First time, last month, I lost one cylinder only, this past weekend engine quit altogether. I let it sit for 10 minutes, and it starts perfect. Run under the rain, quits againg. I suspect the spark plug cables are leaking their juice while wet. Does anyone know of a set that is 100% waterproof ? This bike I have ridden for 10 years rain or shine, every day, I guess is time for some love and care...
     
  2. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    Is a 2005 T100 Bonneville.
     
  3. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,358
    800
    Nr Biggar
    The high tension cable insulation is maybe cracked but it could also be arcing from the plug cap to the cylinder head. Either way bypasses the spark plug! Engine heat dries things out.....
    They are cheap and easy to make up with parts from any auto factor. I find the easiest way to detect the source of the problem is in darkness!
     
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  4. Callumity

    Callumity Elite Member

    Feb 25, 2017
    3,358
    800
    Nr Biggar
    However, are you certain it is rain? On a bike that age the pick up coil or the ignition coil could also be going intermittent. If water makes blue sparks fair enough but if you can see nothing expect one or other coil breakdown. Tiny cracks open up in the windings and close as the coil cools.
     
    • Agree Agree x 2
  5. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    Thanks Sir, tried darkness no help. Will post final cure... Will try a bottle sprayer to see where is the water affecting the engine...
     
  6. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    Thanks a lot. It is the rain / water no doubt. I ride this bike every single day and this only happens while ridding under rain, and after a few minutes while stopped, it goes away and runs good for a few minutes...
     
  7. Samsgrandad

    Samsgrandad Senior Member

    Dec 15, 2019
    496
    213
    Somerset
    Check the fuel tank vent, sounds strange but these can get blocked when riding in the rain. The test is that next time the bike cuts out in the wet, stop and open the tank cap, if you get a hiss, the sound of a vacuum releasing then your problem is fuel starvation.

    I had this problem on a 2005 T100 myself and the cure was to locate the end of the fuel tank vent pipe, (behind the engine and in front of the swing arm) and cut it at a 45 degree angle with the longer end towards the front of the bike.
    When you have the end of the pipe cut straight across there can be a tendency for it to create a venturi effect and block up with water.
    There is also a one way valve in the vent pipe and this can failed block. It is designed to prevent the leakage of fuel in the event of the bike falling over.
    Simple answer to this is to remove it from the fuel line altogether.
     
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  8. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    That makes a whole lot of sense !!! Matter fact, when the bike starts dying, sounds exactly like when it runs out of gas, one cylinder dies first, then a few seconds later, the second dies. It sounded so “ like out of gas “ that I even switched the gas ti Reserve thinking it was a gas issue !!! When it happened last sunday, the bike would run for maybe 10 minutes after restart, and same happened. Every time I stopped, I dried the tanks top with a towel, it was just very wet. I noticed that even after I ran over a water pond and water just sprayed everything, the bike kept on going strong like nothing had happened, but eventually later, much later, it will die, one cyl first, then the second. I stop, wait, then restart perfectly. I looked at the spark plug wires, and they were dry every time. What you found, is 100% in accordance with what I saw. I will check my gas for water, I will check the vents, I will spray water on the wires, and will check with a hose on the tank petcock if water around the gas cap eventually creates a vacuum and a fuel flow stop. Thanks a whole lot, I got a lot to check !!!!!
     
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  9. Samsgrandad

    Samsgrandad Senior Member

    Dec 15, 2019
    496
    213
    Somerset
    Don't worry about spraying water around the tank or fuel tap. I also don't think that you would have water in the fuel or the bike would not run in the dry.
    The first thing I would check is the pesky one way valve in the fuel vent pipe.
    This is the small pipe that fits on the base of the fuel tank on the right hand side towards the rear. The valve is about half way down the pipe secured to the central part of the frame just behind the carbs. I would be tempted to start by taking that out of the line and discarding it then check the line is clear and try the bike again in the wet.
     
  10. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    Thanks a lot !!! Will post the findings...
     
    • Like Like x 1
  11. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    Here is a photo of the tank fill and gas cap. I tested the airflow on both and found this.... On the tube vent pipe shown inside the tank, with a hose attached, no air flow when vacuum, air flow when pressured a bit. On the gas cap, no air flow when pressured on the threads pipe and some air rather a bit difficult when vacuum the thread pipe. I hope this is normal. We’ll see... image0 2.jpeg
     
  12. Johnnymoto

    Johnnymoto Well-Known Member

    Nov 11, 2020
    45
    68
    Puerto Rico
    Here is a photo of the tank fill and gas cap. I tested the airflow on both and found this.... On the tube vent pipe shown inside the tank, with a hose attached, no air flow when vacuum, air flow when pressured a bit. On the gas cap, no air flow when pressured on the threads pipe and some air rather a bit difficult when vacuum the thread pipe. I hope this is normal. We’ll see... View attachment 113203
     
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