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Thread: 350x starting help

  1. #1
    Join Date
    Jun 2014
    Location
    Oregon,Medford
    --
    67

    350x starting help

    so i just took my head off to replace gaskets and remove broken exhaust studs everything appeared to go smoothly until i got it back together and tried to start it. i kicked and kicked and some time later i got it to fire and now it only stays running revved at half throttle and studders and if i let off the gas it will die. after its warmed up i sometimes can start it and sometimes i give up kicking till the next day. any direction guesses or help would be much appreciated.

  2. #2
    Join Date
    May 2009
    Location
    S.E. Michigan
    --
    1,251
    It could be a lot of things: valve timing could be off, head gasket could be leaky, valve lash could be misadjusted, decompression cable could be misadjusted, carb may have gotten hosed or has an air leak at the manifold.

    Valve timing will be the most intrusive to check and fix, but unless you are 100% certain it is right, probably should be checked. Then valve lash next.

    Do you have the manual? It will give you lots of instructions for all these tasks.
    http://www.kb0nly.info/ATC/index.php?dir=ATC350X%2F
    - Frank

    1984 200ES Big Red
    1985 350X (x2)
    1986 350X
    1986 250SX
    1984 Auto-X
    1984 ATC70
    1985 ATC70

  3. #3
    Join Date
    Aug 2008
    Location
    devore,ca
    --
    1,042
    My guess would be timing.
    YAMAHA 450 HYBRID
    85 350X- RED
    85 350x -BLACK
    86 350x-WHITE (with Goki)
    85 250r
    83 atc 70
    84 atc 70
    84 atc 110
    09 yfz 450
    2006 Arctic Cat Prowler
    RZR XP 900

  4. #4
    Join Date
    Jun 2014
    Location
    Oregon,Medford
    --
    67
    well i just tore it down and moved chain one tooth and now it only sputters for a second and wont start im lost i need to see a picture and exact process for guaranteeing correct timing chain installation

  5. #5
    Join Date
    May 2009
    Location
    S.E. Michigan
    --
    1,251
    Quote Originally Posted by heusser85 View Post
    i need to see a picture and exact process for guaranteeing correct timing chain installation
    ...please download the service manual from the link I posted above. It will give you EXACTLY what you are looking for. Refer to page 6-14 for your picture and instructions.

    Also, please pay particular attention to page 6-17 regarding installation of the head cover. You need to be careful where you put sealant. You need to keep it away from the areas around the cam bearings. If sealant gets in there, you can damage (destroy) the bearing surfaces.


    Here is the "Cliff's Notes" version:
    Cam lobes down
    Flywheel "T" marked aligned with index
    Cam sprocket lines on back side aligned even with upper surface of head
    Bolt it all together
    Last edited by wonderboy; 08-14-2014 at 08:28 AM.
    - Frank

    1984 200ES Big Red
    1985 350X (x2)
    1986 350X
    1986 250SX
    1984 Auto-X
    1984 ATC70
    1985 ATC70

  6. #6
    Join Date
    Aug 2008
    Location
    devore,ca
    --
    1,042
    Lobes down,center punch mark on the sprocket up, timing marks lined up on the fly wheel and cover, timing lines on the sprocket flat with the top of the head. Install chain tensioner and check to make sure everything is still lined up.
    YAMAHA 450 HYBRID
    85 350X- RED
    85 350x -BLACK
    86 350x-WHITE (with Goki)
    85 250r
    83 atc 70
    84 atc 70
    84 atc 110
    09 yfz 450
    2006 Arctic Cat Prowler
    RZR XP 900

  7. #7
    Join Date
    Jun 2014
    Location
    Oregon,Medford
    --
    67
    thanks for the help the cliff notes are exactly how i did it the first time and it ran like so i changed it and now it runs worse so i have to put it back to where i had it and seek out a different option.

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