2004-2009 Suzuki LT-Z250 Service Manual, Page 67Get this manual
After fitting all valve guides, re-finish their guiding bores with the valve guide reamerBe sure to clean and oil the guide after reaming& 09916-34550: Valve guide reamer (5.5 mm) 09916-34542: Reamer handle NOTE: Insert the reamer from the combustion chamber and always turn the reamer handle clockwiseVALVE SEAT WIDTH Coat the valve seat with prussian blue uniformlyInstall the valve and attach the valve lapper onto itTap the coated seat with the valve face in rotating manner, in order to obtain clear impression of the seating contact& 09916-10911: Valve lapper set
The ring-like dye impression left on the valve face must be continuous, without any breaksIn addition, the width of the dye ring, which is the valve seat width, must be within the following specification Valve seat width Standard: 0.88 1.08 mm (0.035 0.043 in)