Sym Fiddle II 50 Series Service Manual page 75

SYM
Use 60° cutter to cut a quarter lower part out.
Remove the cutter and check new valve
seat.
Use 45° cutter to grind the valve seat to
specified width.
Caution
Make sure that all roughness and
uneven faces had been grinded.
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 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.
6. CYLINDER HEAD/VALVE
Contact surface too high
Contact surface
too low
Old valve seat width
60°
1.0mm
45°
Old valve seat
width
32°
Old valve seat
width
60°
6-11