Sym MB10A7-A series Service Manual page 115

7. Cylinder Head / Valve
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Use the 45 degree cutter and cut the seat to
the proper width.
Caution
Confirm that all roughness is removed.
Grind valve seat again if necessary.
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 is 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 grinding the valve seat, coat the valve
seat surface with emery and then slightly grind
the valve seat with the valve by using
specified grinding driver.
Clean up all emery coated on the valve seat
and valve after grinding.
Caution
Do not let the emery into the valve guide.
Clean out all the emery, and apply some
red lead paint onto the valve seat contact
face.
7-14
To this chapter contents
Contact surface too high
Contact surface too low
1.0mm
45°
Old valve seat width
32°
Old valve seat width
60°