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Quick cam timing question - 180 off?

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  • Quick cam timing question - 180 off?

    I have a feeling this has already been covered but I can't manage to find anything useful with my searches, so here goes:

    I'm reinstalling my cam shafts after having changed the valve shims. I've made sure to keep tension on the cam chain the whole time, so it doesn't slip on the crank, and I've made sure to keep the two cam sprockets on the chain so that the three gears are all in the same (=correct) location as before. I'm ready to bolt the cam sprockets to the shafts, but how do I know I'm not 180 degrees off?

    I know you're supposed to have the crankshaft at the "T" mark and the cam bearing cap arrows should point at the dots. But this being a 4-stroke and all, if you were to turn the crankshaft 360 degrees, it would be back at the "T" but the cam dots would now be 180 degrees off. So how do you know?

    I have the feeling it might not matter, because if this is like the other bike I've worked on, there's a "wasted" spark in the cylinder at the beginning of the intake stroke. But I want to know for sure before I put it all back together!

    Thanks guys/girls,

    Marshall
    Ann Arbor, MI; Needham, MA
    1980 Yamaha XS1100 Midnight Special
    1983 Kawasaki gpZ550
    1978 Kawasaki KZ650

  • #2
    The cams are what delineates whether the motor is 180deg off or not.

    If your mark is at the T (top dead center) and you align the cams so that the arrow on the #3 caps is pointing at the dot on the cams, you are correct.

    It's pretty fool-proof, actually. Just make sure your cam tensioner is FULLY seated before you try and start the bike.

    DAMHIK!
    Nice day, if it doesn't rain...

    '05 ST1300
    '83 502/502 Monte Carlo for sale/trade

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    • #3
      Thanks! I'll get right to it...
      Ann Arbor, MI; Needham, MA
      1980 Yamaha XS1100 Midnight Special
      1983 Kawasaki gpZ550
      1978 Kawasaki KZ650

      Comment


      • #4
        Also pay attention to the direction of rotation when you tighten up the cam chain to check, wrong direction and you will be out of time, and possibly/probably bend valves.
        Life is what happens while your planning everything else!

        When your work speaks for itself, don't interrupt.

        81 XS1100 Special - Humpty Dumpty
        80 XS1100 Special - Project Resurrection


        Previously owned
        93 GSX600F
        80 XS1100 Special - Ruby
        81 XS1100 Special
        81 CB750 C
        80 CB750 C
        78 XS750

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