SANYANG INDUSTRY CO. SYM, Service Manual

Page: 71 / 176

6. CYLINDER HEAD/VALVE SYM
6-10
Hold the cylinder head, and then press out old
valve guide from combustion chamber side.
Tool: Valve guide driver 5 mm
Caution
Adjust the valve guide driver and let valve
guide height is in 13mm.
Press in new valve guide from rocker arm side.
Tool: Valve guide driver 5 mm
Wait for the cylinder head cooling down to
room temperature, and then correct the new
valve guide with reamer.
Caution
Correct valve seat, and clean up all metal
residues from cylinder head.
Special tool: Valve guide reamer 5 mm
VALVE SEAT INSPECTION AND
SERVICE
Clean up all carbon deposits onto intake and
exhaust valves.
Apply with emery slightly onto valve contact
face. Grind valve seat with a rubber hose or
other manual grinding tool.
Caution
Remove the valve and check its contact
face.
Caution
y
Check if new valve guide is deformation
after pressed it in.
y
When pressing in the new valve guide,
cylinder head still must be kept in 100~150
℃
.
y
Using cutting oil when correcting valve
guide with a reamer.
y
Turn the reamer in same direction when it
be inserted or rotated.
y
Do not let emery enter into between valve
stem and valve guide.
y
Clean up the emery after corrected, and
apply with red paint onto contact faces of
valve and valve seat.
Replace the valve with new one if valve
seat is roughness, wear out, or incomplete
contacted with valve seat.
If the valve and the valve seat still can not
be matched sealing after grinded, replace it
with new one.
valve seat
width
Valve guide driver
5.0mm
13 mm
(0.15in)
Valve guide reamer 5.0mm
Valve seat
width