This bearing will fit a 2000 mxz 600. Wiseco sells the bearing for this model. Stock dimensions for the upper connecting rod bearing are ( 20x25x23)mm. Kimpex sells a upper connecting rod beraing that is (20x25x24)mm. Now the extra mm in length takes up the space of the 2 factory shims on factory cageless bearing. Put over 1000 miles on this setup, no problems.