1998-2006 Yamaha F20/F25 Outboards Service Manual, Page 169Get this manual
CAMSHAFT AND VALVES
Valve guide replacement Replacement steps:
NOTE: Heat the cylinder in an oven to 200 (392 to ease valve guide removal and F) installation, and to maintain the correct interference fit Remove the valve guide with the valve guide removerValve guide remover: YM-0112290890-04016 Install the circlip and the new valve guide with the valve guide installer and valve guide removerValve guide installer: YM-401590890-04016 After installing the valve guide, bore the valve guide with the valve guide reamer to obtain the proper valvestem-to-valve-guide clearanceValve guide reamer: YM-0119690890-04016