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Cam and valnv timing

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  • Cam and valnv timing

    When I installed the camshafts I put the one and four cylinders at TDC, just like the manual says and I lined up the dots on the cams with the arrows. It was perfect when I installed the sprocket bolts. Today, before I was going to install the cam chain tightener I rolled the engine around again to make sure I had doen it correctly. Now the dots are not perfect anymore. They come just - just - short of being deadon. I mean just short. Maybe an eighth of an inch or less. It looks like adjusting the chain on the sprocket by a tooth would be too large an adjustment.too small a distance to adjust the chain on the sprockets by a tooth to make it up. Is this timing correct? Is it unusualy to have the dots just a touch advanced? (Retarded?) Could I have installed the cams 180 degress off?

    Another issue. When the cylinders are at TDC the arrow indicator by the timing plate is at the limit of its adjustment to hit the "T" mark.

    Did I do something wrong here? I usually get the valve timing spot on and this is concerning me.

    Thanks,

    Patrick
    The glorious rays of the rising sun exist only to create shadows in which doom may hide.

    XS11F (Incubus, daily rider)
    1969 Yamaha DT1B
    Five other bikes whose names do not begin with "Y"

  • #2
    Not good idea to rotate engine w/o pressure on cam chain, by hand or any other way. Even new chain can jump a tooth.

    Before setting the cams, set the "T" mark on timing plate.
    Get #1 piston as near perfect to TDC as you can, then align pointer to "T" mark.

    There is inherently a little "slop" in a chain, but not much.
    Install tensioner before rotating to check cams are where you want em.


    mro
    Last edited by mro; 09-25-2006, 08:18 PM.

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    • #3
      "Hey, Slacker...!"

      As the cam chain stretches with use, alignment 'looks' loopier and loopier due to the slack between the chain's links.
      Bring the crank back to the "T"(if you over shoot it, go around twice and hit it again. I say twice, as you already have the cams in, and if you go only once, your cam marks will be 180 out and you can't see them)
      Your cam marks should be reasonably close. (keep tension on the intake side of the chain) If, by jumping the chain a tooth it gets them closer, go ahead and do it, but I think you know what you're doing. The chain has slack between the links, and your marks will be a little off. Normal.
      Like you did... always when clowning with the timing, roate the engine by hand to ensure all is well and nothing hits anything else.
      "Damn it Jim, I'm a doctor, not a mechanic!' ('Bones' McCoy)

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