Sym Citycom 300i - Page 129

6. Cylinder Head / Valve
6-12
Use 60ƒ cutter to cut a quarter lower parts out.
Remove the cutter and check new valve seat.
Use 45ƒ cutter to grind the valve seat to specified
width.
Caution

Make sure that all roughness and uneven faces
had been ground.
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 32ƒ cutter.
Then, grind the valve seat to specified width.
If the contact surface too low, grind the valve seat
with 60ƒ cutter.
Then, grind the valve seat to specified width.
Old valve seat width
60‚
1.0mm
60‚
45‚
32‚
Old valve seat width
Contact surface too high
Old valve seat width
Contact surface too low
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