Suzuki DF 25 Service Manual page 147

7-30 POWER UNIT
VALVE SEAT SERVICING
If valve seat contact width is out of specification, reface valve
seat as follows:
• Valve seat angle
Intake side
Exhaust side
09916-20620 : Valve seat cutter 45° ° ° ° ° (NEWAY122)
09916-20610 : Valve seat cutter 15° ° ° ° ° (NEWAY121)
09916-24440 : Handle adaptor (N-503-1)
09916-24450 : Solid pilot (N-100-5.52)
09916-54910 : Handle (N-505)
NOTE:
Turn cutter clockwise, never counterclockwise.
(1) Remove all carbon from valve and valve seat.
(2) Using 45° angle cutter, reface valve seat.
(3) Check valve seat contact width A.
See the "Valve seat contact width" section on page 7-29.
(4) If width A is too high (or wide), reface valve seat using 15°.
If width A is too low (or narrow), reface valve seat using 45°
angle cutter.
(5) Clean up any burrs using 45° angle cutter very lightly.
Grind seat areas minimally only.
Do not grind more than necessary.
(6) Lap valve on seat in two steps, first with coarse grit lapping
compound applied to face and the second with fine grit com-
pound.
(7) Recheck valve seat contact width A.
: 15° ° ° ° ° , 45° ° ° ° °
: 15° ° ° ° ° , 45° ° ° ° °
IN, EX
Valve seat
15˚
45˚
• Too high (wide)
• Too low (narrow)