Suzuki EN125-2A, Service Manual

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ENGINE 3-18
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.
After the desired seat position and width is
achieved, use the 45 cutter very lightly to clean
up any burrs caused by the previous cutting
operations.
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Clean and assemble the head and valve
components. Fill the intake and exhaust ports
with gasoline to check for leaks. If any leaks
occur, inspect the valve seat and face for burrs
or other things that could prevent the valve from
sealing.
4.
5.
If the contact area is too high or too wide, use the
15 cutter (for exhaust side) and 30 /60 cutters
(for intake side) to lower and narrow the contact
area.
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If the contact area is too low or too narrow, use the
45 cutter to raise and widen the contact area.
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WARNING:
Always use extreme caution when handling
gasoline.
NOTE:
Be sure to adjust the valve clearance after
reassembling the engine.
Insert with a slight rotation, the solid pilot that
gives a snug fit. The shoulder on the pilot
should be about 10 mm from the valve guide.
Using the 45 cutter, descale and cleanup the
seat with one or two turns.
Inspect the seat by the previous seat width
measurement procedure. If the seat is pitted or
burned, additional seat conditioning with the
45 cutter is required.
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1.
2.
3.
CAUTION:
DO NOT use lapping compound after the
final cut is made. The finished valve seat
should have a velvety smooth finish and not
a highly polished or shiny finish. This will
provide a soft surface for the final seating of
the valve which will occur during the first few
seconds of engine operation.