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.

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 ????

Quote:

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Originally Posted by byrdsperformance@tds.net

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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Pre-mix

Thanks Mike

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

Jeff

more often than not oil pump not made to turn 6500 - 8000

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

Thank's (Jeff)