Do flywheel weights wear out crank bearings quicker

holeshot413
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holeshot413
I have a buddy whose mechanic told him this because he lost the left side crank bearing twice in 3 years.
I disagree
Any thoughts out there
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project racer 12/27/2019 11:58pm
12/27/2019 11:58pm Edited Date/Time 12/28/2019 12:02am
Removed the internal rotor system on a 79 YZ250 engine. Replaced with external flywheel system from a 1987 YZ80, also had Moose add 14 ounces to the flywheel, balanced. Lost the LH main bearing in about 20 races on a new build.

Engine was in a Champion frame short track bike. The bearings had those crappy plastic separators. Broke the plastic, all the balls rolled together.
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kb228
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kb228 12/28/2019 4:11am
12/28/2019 4:11am
more weight on the bearing the quicker they wear.
Momus
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Momus 12/29/2019 12:38am
12/29/2019 12:38am
holeshot413 wrote:
I have a buddy whose mechanic told him this because he lost the left side crank bearing twice in 3 years. I disagree Any thoughts out...
I have a buddy whose mechanic told him this because he lost the left side crank bearing twice in 3 years.
I disagree
Any thoughts out there
Bad handling of the main bearing install is common and the likely cause of early failure.
Another reason could be an out of balance weight.

Another could be not using the correct C clearance and the bearing running very hot- which they tend to do on the magneto side.
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BikePilot
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BikePilot 12/31/2019 6:43am
12/31/2019 6:43am
Yes an out of balance weight is hard on a crank. A balanced weight won't make a measureable difference. My woods-prepped CR250R has several hundred hours on the bottom end with a eline external stator. The stator rotor is essentially a magnetic flywheel weight.
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holeshot413
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holeshot413 1/1/2020 8:22pm
1/1/2020 8:22pm Edited Date/Time 1/2/2020 9:49pm
BikePilot wrote:
Yes an out of balance weight is hard on a crank. A balanced weight won't make a measureable difference. My woods-prepped CR250R has several hundred hours...
Yes an out of balance weight is hard on a crank. A balanced weight won't make a measureable difference. My woods-prepped CR250R has several hundred hours on the bottom end with a eline external stator. The stator rotor is essentially a magnetic flywheel weight.
I’m running a stealy 11 oz?

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