2001 Polaris Sportsman 400-500 DUSE and H.O. Service Manual, Page 125Get this manual
END PLAY INSPECTIONADJUSTMENT
Before reassembling the crankcase,the following steps should be performed to determine the amount of crankshaft, counter balancer shaft, and pump shaft end playExcessive end play may cause engine noise at idle and slow speedsToo little play will side load the bearings which may lead to premature bearing failure
CRANKSHAFT END PLAY ADJUSTMENT