Cylinder Head Reassembly - Sym EuroMX 125 Service Manual

6. Cylinder Head/Valve
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
The contact surfaces of valve and valve seat
are very important to the valve sealing
capacity.
If the contact surface too high, grind the valve
seat with 32° cutter.
Then, grind the valve seat to specified width.
If the contact surface too low, grind the valve seat
with 60° cutter.
Then, grind the valve seat 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 closed coils of valve spring should face
down to combustion chamber.
6-12
This chapter Contents
Contact surface
too high
Contact surface
too low
Spring
retainer
Valve spring
Old valve seat
width
Valve split
locks
Old valve seat
width
32°
60°
Valve stem
oil seal
Valve