SANYANG INDUSTRY CO. SYM, Service Manual

Page: 73 / 176

6. CYLINDER HEAD/VALVE SYM
6-12
Coat the valve seat surface with red paint.
Install the valve through valve guide until the
valve contacting with valve seat, slightly
press down the valve but do not rotate it so
that a seal track will be created on contact
surface.
Caution
If the contact surface too high, grind the
valve seat with 32° cutter.
Then, grind the valve seat with 45° cutter to
specified width.
If the contact surface too low, grind the valve
seat with 60° cutter.
Then, grind the valve seat with 45° cutter to
specified width.
After the valve seat grinded, coat valve seat
surface with emery and then slightly press
the grinded surface.
Clean up all emery coated onto cylinder and
valve after grinded.
CYLINDER HEAD REASSEMBLY
Lubricate valve stem with engine oil, and
then insert the valve into valve guide.
Install new valve stem oil seal.
Install valve springs and retainers.
Caution
The contact surfaces of valve and valve
seat are very important to the valve sealing
capacity.
The closed coils of valve spring should face
down to combustion chamber.
Contact surface too high
32°
Old valve seat
width
Contact surface
too low
60°
Old valve seat
width
Valve
Valve stem
oil seal
Valve spring
Valve spring
retainer
Valve cotters