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Thread: Smokey 250es

  1. #1
    Join Date
    Mar 2003
    Location
    Australia
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    1,919

    Smokey 250es

    Gday.

    FInally got round to rebuilding my 250es top end today with a new piston, rings, gasket set and bore job. I also painted it all up and tidied it up somewhat (pics will be to follow for anyone interested). Now on starting it up it was really really smokey and kept on blowing out loads of smoke for about 15 minutes on idle. I then took it for a little drive for about 2 minutes (not thrashing it, it has to be broken in) and stopped it, let it cool down a tad, and restarted it and the smoking was gone.

    My question is it normal for the motor to run really smokey for a few minutes after it has just had a fresh top end put in it? What causes this?

    Thanks

    Matt
    1980 ATC 70 Needs Restoration
    1985 ATC 250es Fully Refurbed
    1986 ATC 350x Mint Original

  2. #2
    Join Date
    Feb 2006
    Location
    Arkansas
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    5
    Rings probably needed to seat. also did you rotate the compression ring opposite the oil rings? It might be letting some oil pass which would cause it to smoke. Most likely the rings just needed to seat though.
    TOYS
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  3. #3
    Howdy's Avatar
    Howdy is offline Putting Priorities in Order, Busier than ever. Catch me if you can
    Join Date
    Sep 2002
    Location
    Celina, Ohio
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    10,079
    Quote Originally Posted by stunter
    Rings probably needed to seat. also did you rotate the compression ring opposite the oil rings? It might be letting some oil pass which would cause it to smoke. Most likely the rings just needed to seat though.
    It was also probably burning off any extra oil that was put on the cylinder when installing the piston.
    Howdy

  4. #4
    Join Date
    Sep 2004
    Location
    Brandon, Manitoba
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    2,209
    I agree with Howdy
    When I started mine up right after I rebuilt it, it was kind of smokey and fouled a plug up a little. I ran it til the smoke cleared and replaced the plug, now its perfect. I would say if the smoke has stopped, replace you plug.

  5. #5
    Join Date
    Sep 2005
    Location
    wisconsin
    --
    475
    your valve seals also might need replacing

  6. #6
    Join Date
    Sep 2004
    Location
    springville, PA
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    6,185
    It was just burning off the oil. If the seals were bad it would still smoke like a SOB
    Nate

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  7. #7
    Join Date
    Mar 2003
    Location
    Australia
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    1,919
    Yep Thats probably what it was come to think of it! Cheers Guys!
    1980 ATC 70 Needs Restoration
    1985 ATC 250es Fully Refurbed
    1986 ATC 350x Mint Original

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