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  1. #1

    Yamaha 1100 crank indexing - twisted crank?

    I am working on an 1100 triple. It is backfiring badly on #2 and #3.
    I brought #1 to TDC and measured the depths of #2 and #3. It is my understanding that they should be at equal heights. They're not - more than 1 inch apart.
    I also did this with #2 and measured #1 and #3. Same results.

    Before I put a degree wheel on it - does anyone here agree/disagree that I have a badly twisted crank here?

    PS. Electronics, reeds, carbs, crank seals are all good.

  2. #2
    I pulled the flywheel cover once again and did a quick & rough indexing. #2 and #3 are roughly 1/3 of a rotation (120 degrees) apart, but #1 and #2 are about 60 degrees apart (1/6 rotation).

    I daresay I have found the problem.

  3. #3
    SurfRider's Avatar
    Join Date
    Jun 2010
    Glad you finally got to the bottom of this mystery! Yeah, I would think that they all should be 1/3 of a rotation apart. :P

  4. #4

    Join Date
    Jul 2005
    Central North Carolina
    Correct 120 degrees between each piston rotation to top dead center. look at this link also

  5. #5
    SurfRider's Avatar
    Join Date
    Jun 2010
    Thanks for the diagram, but what I really wanted to see was pictures of an actual crank disassembled. I was wondering how they had the rod connected to the crank without having them split and this explains this. I'm guessing that they would have to separate at the fly weights. I would think that if it were twisted the crank would no longer be straight at the main journals. If they were 1/6 off, I would think that should destroy the case?

  6. #6
    The individual webs are joined by press-fit pins.
    I'll take some pics if and when I take this one apart.

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