Yamaha 40/50hp 3 cyl 2-stroke

[Koondog]

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.

[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 ????

[Koondog]

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

[Koondog]

Thanks Mike

[Fastjeff57]

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

Jeff

[sabine river killer]

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

[byrdsperformance@tds.net]

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

Thank's (Jeff)