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Thread: 1992 K100RS Any advice?

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  1. #1
    Kbiker BCKRider's Avatar
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    1992 K100RS Any advice?

    (Sorry about the long story - may help you diagnose the problem and solution.)

    Last Sunday left on a 330 mile trip to fish with a friend, bike running great. Stopped for gas and after filling up, noticed there was a tanker truck parked on the premises. (Yes, I have heard you should go to the next station when you see that, and no, I wasn't paying attention.) Go over a hundred miles, bike still running perfectly, and am within 50 miles of my destination when the bike suddenly won't accelerate.

    There is maybe a five minute period where I can maintain 60 mph but without the usual acceleration when I roll on the throttle. Then suddenly all the power is back. Then there are a few "power cuts" of a second or so and immediate restitution of normal power. Then another several minute cut of power with another restitution of power which lasted until I got to my friend's place. I'm thinking "bad gas" and the next day bought a can of Sea Foam, added half of it to the near empty tank, filled up the tank and took the bike for a 20 mile ride. Great power; no problems. Parked the bike in friends garage for a few days while we fished. (Not relevant, but yesterday caught three trout over 3 pounds - kept one - on the most improbable #14 dry fly fished deep on a sinking line!)

    The first 120 miles of my trip home today were absolutely free of any bike problems. Then the loss of power returned, and stayed. Adding the rest of the Sea Foam and filling the tank didn't help. So I had something like 200 miles of rainy mountain pass riding on a bike that had something like a third of its 100 hp - always wondering if it was going to simply quit. Gear kept me warm and dry, but it was a scary trip. Did make it home.

    A guy working at our place (former bike owner and one who had recently done some work on his old Volvo and failed to install one spark plug wire) suggested it sounded like the bike was running on three of its four cyclinders.

    So, what say you about the plausible causes of the problems (and also the chance I've done terrible damage to the engine?) I'm thinking the most probable cause of the intermittent problems was not water in the gas but small grit which passed through the fuel injectors and, finally, a piece which blocked a single injector. But I know next to nothing about engines.

    I clearly will have to take this bike to a mechanic - and it does still run, barely. Your advice would be most helpful if there are other possibilities which fit the symptoms described but have nothing to do with water or particles in the gas. That COULD have simply been a coincidence.

    Thanks in advance for your thoughts.
    Doug
    1992 K100RS

  2. #2
    3 Red Bricks
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    Pull the fuel filter. Pour out the gas in the filter, then let the filter dry out for a couple of hours.

    Then lightly blow through the filter in the direction of the arrow. If you feel ANY resistance, it's time to change the filter. If you feel real resistance, it's probably the major part or all of your problem. Change the filter and see how it runs.


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    Lee Fulton Forum Moderator
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  3. #3
    Brick Pilot der ziegelstein's Avatar
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    What Lee said.

    I experienced the exact symptoms on my way home from work last month. I replaced the fuel filter, all is well.
    Jim McGill
    '87 K100RS
    '04 R1150RT

  4. #4
    Registered User Overkill's Avatar
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    If you are not comfortable pulling the fuel filter yourself you might drain the gas and see if there is water in it. If you put it in a clear glass container it will be VERY obvious. The water will be on the bottom (after a few minutes to settle) and there will be a very clear line where the water ends and the gas starts. If there is no line then there is no water. But even if it is water and not debris that you picked up then you should probably replace the fuel filer anyway. So I'm not sure if I helped at all!
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    Kbiker BCKRider's Avatar
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    changing the fuel filter didn't work

    The problem is back to the "intermittent" stage - full power maybe 20% of the time, lacking power 80% of the time.

    Three other clues I forgot to mention in the OP: 1. the bike used almost twice as much fuel as normal while running badly, 2. the idle is slower than normal and the engine just sounds rough when it lacks normal power and 3. the change from full power to little power and vice versa is instantaneous - it is just as suddenly running well as running badly.

    Any thoughts on what to check next?
    Doug
    1992 K100RS

  6. #6
    Registered User WalterK75's Avatar
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    I had a loss of power on a 1991 K75 which turned out to be the heat sensor in the engine. I don't know if this could be your problem.
    Walter

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  7. #7
    3 Red Bricks
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    Quote Originally Posted by BCKRider View Post
    2. the idle is slower than normal and the engine just sounds rough when it lacks normal power and 3. the change from full power to little power and vice versa is instantaneous - it is just as suddenly running well as running badly.

    Any thoughts on what to check next?
    Sounds electrical/spark related.

    Take an inductive timing light or an inductive spark checker and test at each plug wire while it is running poorly. If you find two cylinders not firing properly, see if they are on the same coil. Could be a bad coil.

    Could also be one of the pickups on the Hall Effect sensor starting to fail.

    Insure that the plug to the FI computer is solidly connected. Unplug it and replug it in several times to clean the contacts. Make sure it "CLICKS' when you plug it in.

    Try unplugging the Throttle Position Switch and see if it runs OK with it unplugged.




    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

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