Like I said, it's not what I'd call a common failure, I'm not trying to scare anyone, the XR motor is uber relaible compared to many others.
Ron, that's a great explanation of lubrication's characteristics and I think you're right on the money with it's effects. It sounds like a plausable cause for crypto's prob. The plain brg in the small end is a proven design but there is allot of mass in the crank/rod/piston assy on a 650. Lugging definately taxes the brg areas.