Jianshe JS125-6B, Maintenance Manual

Page: 77 / 210

ENGINE
67
Valve seat
1. Clean
Carbon deposit
(Eliminate from valve face and the valve seat)
2. Check
Valve seat
Pit corrosion or wear Repair valve seat once more
3. Measurement
Valve seat width
Measuring steps
Smear blue dyes (Dykem) onto the working
surface of the valve when overhaul.
Install the valve into the cylinder head.
The valve is push onto the valve seat through the
valve guide, and then got a clear trace.
Measure the width of the trace, that is, the width
of the valve seat. No matter how the valve seat and
valve face contact anywhere, the blue don't disappear.
If the valve seat is too wide, narrow or don't
locate in the center, must repair it once more.
Valve seat width
Intake: 0.9 1.1mm
Exhaust: 0.9 1.1mm
Out of specification Repair valve seat once more
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4. Grind
Working surface of valve
Valve seat
After replacing the valve and the valve guide, must
grind the valve seat and valve face.
Note