2008 Polaris ATV Sportsman 300 400 H.O. Service Manual, Page 80Get this manual
ENGINE (300) Balance Shaft Bearing Inspection
NOTE: Replace all seals whenever the crankcase is disassembled1Inspect the balance shaft bearings in the crankcase
BearingSeal Installation
NOTE: To ease crankcase bearing installation, warm the crankcase until hot to the touchPlacing the bearing in freezer prior to installation will assist the assembly process12Install the bearing so the numbers are visibleDrive or press the new bearing into the crankcase, using the proper driver
NOTE: Due to extremely close tolerances and minimal movement, the bearing must be inspected visually and by feelLook for signs of discoloration, scoring or gallingTurn the inner race of bearingThe bearing should turn smoothly and quietlyThe outer race should fit tightly in the crankcaseThe inner race should be firm with minimal side to side movement and no detectable up and down movement2To remove balance shaft bearings, use blind hole bearing puller