2010 Polaris Sportsman 850 Service Manual, Page 154Get this manual
ENGINE Crankcase Preparation (Lower)
Clean lower crankcase gasket sealing surfacesRefer to Oil Flow Diagram (page 5.4) and trace the oil path from the through the lower crankcaseFlush all passages with solvent and then warm soapy waterRinse with clear warm water and dry with compressed airBe sure passages are clean and dry before assembling the lower crankcaseAssemble parts in order A-J