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  1. #1
    rcab85's Avatar
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    call me crazy!!!! timing chain mystery solved in my head???

    it just occurred to me while riding my friends 15 fzr bone stock, I could actually feel the engine flutter when I let off the gas, this leads me to believe that all the timing chain failures have been on ski's without blow off valves. yamaha's bigger charger combined with more boost and no bov just makes for super intense vibration/flutter jarring the gear driven supercharger to exert extra force back on the crank and the timing chain being the weakest link (no pun intended) just can't take it with all the rpm/bigger pump still spinning and just snaps. if this issue has already been solved and someone already knows why these chains are breaking on stock ski's under factory rev limiter I'm sure you'll just post the link and disregard my rant.


  2. #2
    Slamdcoop0428's Avatar
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    But they have clutches to take the hit. They also have the same part number as my 2013 sho and I'm running way harder then a stock svho. It's a bad batch of chains or a different manufacture with a weaker process of making the chains.

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  4. #3
    zone5's Avatar
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    Doc Einstein ran Relativity as a thought experiment too... He dropped the "cosmological constant" as the biggest blunder of his life when Fred Hoyle came up with his rule for an expanding universe, yet with our ever increasing knowledge of the furthest edges of the universe we may need to sneak something similar back into the picture to make it all work...

    So, the moral of this apocryphal tale is - Don't give up yet, you might be onto something!


    ps: Please, before those whose interest in this topic exceeds mine jump all over it, don't get hung on detail, this was a joke, not a cosmology lesson....

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  6. #4
    rcab85's Avatar
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    the new updated stronger clutches do not take the hit, in my mind the only thing that changed from sho to svho other than pistons is 60% more flutter or surge on the crank and timing chain and I'm curious to find someone who has a blow off valve that broke a chain under stock rpm limiter.

  7. #5
    Slamdcoop0428's Avatar
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    Quote Originally Posted by rcab85 View Post
    the new updated stronger clutches do not take the hit, in my mind the only thing that changed from sho to svho other than pistons is 60% more flutter or surge on the crank and timing chain and I'm curious to find someone who has a blow off valve that broke a chain under stock rpm limiter.
    So you're saying the clutches don't slip? I'm pretty sure they are there to take the hit/shock.

  8. #6
    Slamdcoop0428's Avatar
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    Quote Originally Posted by rcab85 View Post
    the new updated stronger clutches do not take the hit, in my mind the only thing that changed from sho to svho other than pistons is 60% more flutter or surge on the crank and timing chain and I'm curious to find someone who has a blow off valve that broke a chain under stock rpm limiter.
    Also, come ride my 15.5 ski. You don't know what the meaning of flutter is lol and my ski is just fine. I'm on 17 psi.

  9. #7
    rcab85's Avatar
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    I am willing to bet a turbo svho (yamaha's future) with a 14 or 15 timing chain would never break. I am not arguing about the clutch what I'm saying is the bigger charger opening and lack of bov combined with more boost is causing an absurd amount of surge and jarring the chain over and over again until finally it breaks... its a much more logical and mechanically wise theory compared to oh its a bad batch of chains, I call bull and say it's no coinsedence that the bigger charger, bigger volute and more rotational mass between the Pistons and 160 pump is the cause of the failures. if not its the best theory I've heard.

  10. #8
    Slamdcoop0428's Avatar
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    Quote Originally Posted by rcab85 View Post
    I am willing to bet a turbo svho (yamaha's future) with a 14 or 15 timing chain would never break. I am not arguing about the clutch what I'm saying is the bigger charger opening and lack of bov combined with more boost is causing an absurd amount of surge and jarring the chain over and over again until finally it breaks... its a much more logical and mechanically wise theory compared to oh its a bad batch of chains, I call bull and say it's no coinsedence that the bigger charger, bigger volute and more rotational mass between the Pistons and 160 pump is the cause of the failures. if not its the best theory I've heard.
    Then my ski should have fallen apart by now, with all that you're saying with my weaker sho parts.

  11. #9
    Slamdcoop0428's Avatar
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    If you think not having a BOV is the problem then it's not the best theory I've heard.

  12. #10
    Slamdcoop0428's Avatar
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    The clutch is going to absorb most of, if not all of that flutter before the crank/chain feels it.

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