1996-2005 Suzuki DF40, DF50 Four Stroke Outboard Service Manual, Page 178Get this manual
6-35 POWER UNIT NOTE: Clean and assemble cylinder head and valve componentsFill intake and exhaust ports with solvent to check for leaks between valve seat and valveIf any leaks occurinspect valve seat and face for burrs or other things that could prevent valve from sealing
VALVE GUIDE REPLACEMENT
Be careful not to damage cylinder head when replacing valve guide
(1) Using valve guide remover, drive valve guide out from combustion chamber side towards valve spring side09916-44310Valve guide remover