Honda BF8, BF9.9 and BF10 Outboard Motors Shop Manual., Page 163Get this manual
5) Set the valve spring compressor and compress the valve
111 VALVE SPRING COMPRESSOR 07757-0010000
6) Remove the valve cotters, then release the valve spring compressor and remove the spring retainer, valve spring, valve spring seat and valveRemove the valve stem seal if necessaryValve stem seal must be replaced with new one when disassembledStore all parts according the cylinder so they can be placed back in their original position