HYOSUNG Aquila 250 Service Manual page 62

If either requirement is not met, correct the seat by ser-
vicing it as follows.
Valve seat width �
◉ VALVE SEAT SERVICING
The valve seats for both intake and exhaust valves are
angled to present two bevels, 15�and 45� .
Valve seat cutter set : 09916-21110
Use only for 15�of intake side.
15� ×75� Valve seat cutter : 09916-24910
Solid pilot (N-140-5.5) : 09916-24480
CAUTION
The valve seat contact area must be inspected
after each cut.
1. Insert with a slight rotation, the solid pilot that gives a
snug fit. The shoulder on the pilot should be about 10
㎜ from the valve guide.
2. Using the 45�cutter, descale and cleanup the seat
with one or two turns.
3. Inspect the seat by the previous seat width measure-
ment procedure. If the seat is pitted or burned, addi-
tional seat conditioning with the 45�cutter is required.
CAUTION
Cut the minimum amount necessary from the seat to
prevent the possibility of the valve stem becoming
too close to the rocker arm for correct valve contact
angle.
If the contact area is too low or too narrow, use the
45�cutter to raise and widen the contact area. If the
contact area is too high or too wide, use the 15�cut-
ter to lower and narrow the contact area.
Standard
0.9~1.1 mm
ENGINE 3-24
0。
15。
15。
45。
45。
Valve seat