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  1. #1

    Help help big issue!!!

    Today i put my ultra 250 motor all back together with the 260 pistons i set the timing all right and took my time to install everything just like it was.. i started it and it ran like shit its vibrating bad.. my boost and RPM's wont get over 5000 rpm and boost is super low? what did i do wrong?? PLEASE HELP there is no F1 light or nothing i have good oil pressure and new fuel?


  2. #2
    nicjak's Avatar
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    vibrating check timing again if you had a modded wheel make sure you put it back to stock to time?
    spark plugs and leads?
    surely you tightened all inlet clamps from s/c to throttle body

    thats about all it can be

  3. #3
    I left the factory tming wheel on it and never touched it... all new spark plugs!! im lost man do you think it could be crank bearings?

  4. #4
    nicjak's Avatar
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    lost why you would think crank bearings if your oil pressure is ok
    need more info why did you pull it down?
    if you assembled exactly as per the manual it should be ok, sounds more like a shit plug to me have you checked them one could be fouled up
    Quote Originally Posted by ard250x View Post
    I left the factory tming wheel on it and never touched it... all new spark plugs!! im lost man do you think it could be crank bearings?
    boost wont start until at least 5000rpm amyway

  5. #5

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    Quote Originally Posted by ard250x View Post
    Today i put my ultra 250 motor all back together with the 260 pistons i set the timing all right and took my time to install everything just like it was.. i started it and it ran like shit its vibrating bad.. my boost and RPM's wont get over 5000 rpm and boost is super low? what did i do wrong?? PLEASE HELP there is no F1 light or nothing i have good oil pressure and new fuel?
    Tooth off on the timing??? air leak somewhere??? Its probably something simple. Start with the obvious and go from there , try not to over think it.

  6. #6

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    Cam timing! If your supercharger belt is properly tensioned and it's not slipping then cam timing would explain the loss of boost and RPM's do to lack of compression. This is what comes to mind with the information provided.

  7. #7
    Sound more like a boost leak to me.

    As pressure biulds in those rubber tubes.

    Check all your rubber hoses from chager to throttle body.

  8. #8
    Hi newbie here, i dont see why no boost, low rpm and vibration would be caused by boost leak. Sounds more like timing problem or spark plug/wire.

  9. #9
    hilomikey's Avatar
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    did you use new gaskets/ And clean surfaces on intake/exhaust manifolds? Also, if the engine is just 1mm off center it will vibrate somewhat bad. I have also seen motor mounts rubber pieces crack over time. Those need to be checked also. Let us know if this helps or you find the problem

  10. #10
    Maybe 2 spark plug wires are misplaced or the cam shaft timing is messed up by a tooth on either cam. Pop the camshaft cover and set to TDC on 1/4 cylinders as per the manual (rotate crank either way till the piston moves and pick the center between the two rotational points using a home made wire pointer or similar method with a magic marker). Check the camshaft sproket area timing marks.

    rt

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