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Thread: Yamaha 40/50hp 3 cyl 2-stroke

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    Default Yamaha 40/50hp 3 cyl 2-stroke

    Can you mix and match the older cranks with the newer crankcases? Or is it the other way around? Basically, I'm wondering if I can put a 1984 crank in a 1999 crankcase. Which crankcase is better for the survival of the crappy bearings that Yamaha installs on their crankshafts? I love the motors but they seem to eat bearings. Any advice would be greatly appreciated.

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    If the block has the dowel pin notch's any of the 3cyl. 40/50 crank's will swap.
    The earlier year crank's used a dowel pin in the outer bearing race to keep bearing's from spinning in casing.
    The later model's used a dual strip of plastic or nylon im not certian of exact type ove matiral used .
    These use interferace clearance to keep from spinning the outter race.
    Are you doing factory pump, pre mix are what type method ????

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    Quote Originally Posted by byrdsperformance@tds.net View Post
    If the block has the dowel pin notch's any of the 3cyl. 40/50 crank's will swap.
    The earlier year crank's used a dowel pin in the outer bearing race to keep bearing's from spinning in casing.
    The later model's used a dual strip of plastic or nylon im not certian of exact type ove matiral used .
    These use interferace clearance to keep from spinning the outter race.
    Are you doing factory pump, pre mix are what type method ????
    Pre-mix

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    Thanks Mike

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    Super dumb question: Do any of you racers out there NOT run pre-mix?

    Jeff

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    49ci OMC, Alum flat sabine river killer's Avatar
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    more often than not oil pump not made to turn 6500 - 8000
    All boat racers lie, accept me and you, but I am starting to question you.

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    (Super dumb question: ) From his post he make's no metion if his motor is bone stock injectied or what.

    Thank's (Jeff)

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