Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 353Get this manual
CYLINDER, PISTON CAUTION: Do not reuse O-rings and dust sealDo not use shop towel, cloth, gloves, etc when reassemblyAssemble the parts with care not to let the foreign particles and dirt enter the valve body and gear pump assembly1) Clean the parts in the fresh ATFCheck that the parts are free from contamination with dust and dirt before reassembly