Suzuki DF25/DF30 Four Stroke Service Manual, Page 148Get this manual
POWER UNIT 7-31 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 occur, inspect 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