E-TON sport 50 Service Manual page 74

6. CYLINDER HEAD/VALVE
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 red paint 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
seat is roughness, wear out, or incomplete
contacted with valve seat.
If the valve and the valve seat still can not
be matched sealing after grinded, replace it
with new one.
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 grinded with
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 grinded with 45° valve seal
chamfer cutter to correct its seat face.
Use 32° cutter to cut a quarter upper part
out.
6-10
Valve seat
valve seat
width
Roughness
45°
Old valve seat width
32°
E-TON
width