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  1. #1

    2000 Yamaha GP1200r engine problem

    Hello all
    I have a 2000 Yamaha GP1200R and I was told it had low compression when I took the cylinders off I noticed that there is gas in the bottom of the engine where the where the piston rods are connected.

    can anyone tell me what has caused the gas to leak to the bottom of the engine and what I need to look for to get it fixed
    thanks


  2. #2
    jeffg426690's Avatar
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    Are you sure its fuel? What do pistons and cylinders look like? Post up some pics

  3. #3
    Myself's Avatar
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    For starters, somebody left the fuel switch on. Then, there must be bad needles OR seat orings. That's the only way the gas can fill the cases.

  4. #4
    The cylinders are good no damage the top of the pistons are black and before is was tested for compression when it was running it looked like black oil coming from the exhaust. I can post some pics tomorrow of the pistons and cylinders

  5. #5
    butterbean_29512's Avatar
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    There is usually a little oil/fuel mixture in the bottom of the crankcase when an engine is taken apart. Especially if it is oil injected. Did you actually test compression before you tore it apart? If nikasil is good, have the cylinders honed to break the glaze (yep Nikasil has to be honed also) and I recommend OEM pistons, or ProX. ProX is what I run in my 1200r, and I love them!

  6. #6
    It was taken to a shop and they told me it had low compression in the rear cylinder and there was fingertip dead of just gas in the lower end. How would I tell if the pistons are bad or the rings

  7. #7
    jeffg426690's Avatar
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    Do you know what the actual compression #'s were?
    Have the cylinder and piston mic'd, tolerance specs are in the service manual. That will tell you what's what w/ them.
    How many hours are on the motor? It may be that rings were worn and you were getting a decent amount of blow-by.

  8. #8
    I am not sure how many hours are on it. I bought it last year and have been trying to get it working right since then.

    they just told me it had low compression

    not sure why or what caused that much gas in the lower end and what cause the oil to blow out of the exhaust as well not sure if it is all caused by the same problem

  9. #9
    Myself's Avatar
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    Quote Originally Posted by techs21 View Post

    not sure why or what caused that much gas in the lower end and what cause the oil to blow out of the exhaust
    Refer to post #3

  10. #10
    Ok so if the gas switch was not on the ln it can have bad needles or seat orings and that is why there is gas in the lower part and also could that also make it blow oil out the exhaust has well or is that a different problem

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