Valve Seat Inspection And Service - Sym Joyride125 Service Manual

VALVE SEAT INSPECTION AND
SERVICE
Clean up all carbon deposits onto intake and
exhaust valves.
Apply with emery slightly onto valve contact face.
Grind valve seat with a rubber hose or other
manual grinding tool.
Caution
Do not let emery enter into between valve
stem and valve guide.
Clean up the emery after corrected, and
apply with engine oil onto contact faces of
valve and valve seat.
Remove the valve and check its contact face.
Caution
Replace the valve with new one if valve
seal is roughness, wear out, or
incomplete contacted with valve seat.
Valve seat inspection
If the valve seat is too width, narrow or rough,
correct it.
Valve seat width
Service limit: 1.6mm
Check the contact condition of valve seat.
Valve seat grinding
The worn valve seat has to be ground with valve
seat chamfer cutter.
Refer to operation manual of the valve seat
chamfer cutter.
Use 45° valve seat chamfer cutter to cut any rough
or uneven surface from valve seat.
Caution
After valve guide had been replaced, it
has to be ground with 45° valve seal
chamfer cutter to correct its seat face.
Use 32° cutter to cut a quarter upper part out.
6. CYLINDER HEAD/VALVE
To this chapter contents
Valve seat
width
Roughness
45°
Old valve seat width
32°
6-9