There is no 60.7 x 1 o-ring on the outer race of the center bearing. And no corresponding groove on the bottom engine case:

http://www.bikepics.com/pictures/2142871/

Here the upper engine case has a lubrication groove corresonding to the holes in the center bearing.

http://www.bikepics.com/pictures/2142876/

Shouldn't the bottom engine case also have this groove?

Now i am only more confused.
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MC21R9N track
MC18R2J track
CBR954
CR250