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Thread: 1986 250SX head noise and jetting questions

  1. #1
    Join Date
    Aug 2023
    Location
    Washington
    --
    2

    1986 250SX head noise and jetting questions

    When idling and when you give it throttle it quite literally sounds like a lathe cutting metal (look it up!). The noise is quiet but noticeable if you listen. It is not obscenely loud but you can tell. It' s kind of concerning, but the thing has had a fair share of ride time and it has not gotten worse. I just really don't like it but have no time to investigate. Anyone have a clue what this could be to point me in the right direction when I one day get to look at it? Also has anyone put a K and N filter on their bike? I need to jet mine because the thing has no balls when you on the throttle and runs too rich, any advice is much appreciated

  2. #2
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,757
    The most common noise on that model are worn out timing chains and guides .
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
    83 atc70/108cc Powroll blue Xmas Special
    81 atc185s HP-ATC full suspension

    Performance Shop is Open PM me for Service

    My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10

  3. #3
    Join Date
    Aug 2023
    Location
    Washington
    --
    2
    Quote Originally Posted by shortline10 View Post
    The most common noise on that model are worn out timing chains and guides .
    https://photos.app.goo.gl/GxLxN75bP68t9b6D9 heres a video of the noise, thinking about it maybe the cam chain could have totally worn through and is now rubbing on the tensioner? I guess the only way to know for sure is to take it apart... for now it is fine haha

  4. #4
    Join Date
    Jul 2009
    Location
    South Florida
    --
    6,757
    Easy repair . Check out this thread . If you pull the tensioner just make sure your piston is at top dead center .

    https://www.3wheelerworld.com/showth...50sx+tensioner
    78 atc 90/180cc Dickson Full Suspension
    76 ATC90/180cc Nicholson
    77 atc 90 Dickson Full Suspension
    84 KLT 110/123cc Powroll Racer from 80s
    87 atc 125m stock
    84 atc 200x Curtis Sparks
    84 atc 200x Powroll My race bike from 80's
    83 atc70/108cc Powroll blue Xmas Special
    81 atc185s HP-ATC full suspension

    Performance Shop is Open PM me for Service

    My Feedback http://www.3wheelerworld.com/showthr...ck+shortline10

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