Suzuki GSF650S Service Manual page 71

FINAL SEAT CUT
• If the contact area is too low or too narrow, use the 45° cutter
to raise and widen the contact area.
NOTE:
After cutting the 15° angle, it is possible that the valve seat (45°)
is too narrow. If so, re-cut the valve seat to the correct width.
• After the desired seat position and width is achieved, use the
45° cutter very lightly to clean up any burrs caused by the pre-
vious cutting operations.
$
Do not use lapping compound after the final cut is
made. The finished valve seat should have a velvety
smooth finish but not a highly polished or shiny fin-
ish. This will provide a soft surface for the final seat-
ing of the valve which will occur during the first few
seconds of engine operation.
NOTE:
After servicing the valve seats, be sure to check the valve clear-
ance after the cylinder head has been reinstalled. (!2-4)
VALVE SEAT SEALING CONDITION
Clean and assemble the cylinder head and valve components.
Fill the intake and exhaust ports with gasoline to check for leaks.
If any leaks occur, inspect the valve seat and face for burrs or
other things that could prevent the valve from sealing.
*
Always use extreme caution when handling gasoline.
NOTE:
After servicing the valve seats, be sure to check the valve clear-
ance after the cylinder head has been reinstalled. (!2-4)
VALVE STEM END CONDITION
Inspect the valve stem end face for pitting and wear. If pitting or
wear is present, resurface the valve stem end. Make sure that
the length 1 is not less than 2.5 mm. If this length becomes less
than 2.5 mm, replace the valve.
( Valve stem end length
Service Limit: 2.5 mm
Contact area too low and too
narrow on face of valve
45˚
ENGINE 3-35