Most likely caused by the lack of the circlip on the output shaft, allowing too much end play, thus tearing up the bearing. For more details, check out:
'05.5 950 Adventure S "Bad Mutha F@&ker"
'04 R1150RTP "cop motor, cop suspension.."
'00 XR650R Dual Sport "Lil' Mule"
Conti TKC80 tire swing
"I don't know what you do, but I know what I do, and I don't do that." --Uncle Doug, R.I.P.
"Without the possibility of death, adventure is not possible"--Reinhold Messner