The original bearing didn't have enough clearance between the bearing and the crank journal.
Some good info can be found in this article from Lang Racing:
https://www.langracing.com/finding-a...aring-failure/
As far as I know, theirs is the only "solution" to the issue. The OEM bearing is too small. They offer a wider bearing. Of course, this means you have to replace the crank and connecting rods...
Also some good info from BE Bearings (this rod bearing problem is even worse on the S65 and S85 motors):
http://www.bebearings.com/store/inde...products_id=27