Yamaha YP250 Mobility Scooter User Manual


 
4-19
VALVES AND VALVE SPRINGS
ENG
NOTE:
NOTE:
*****************************************************
NOTE:
D Turn the valve until the valve face and valve
seat are evenly polished, then clean off all
compound.
For best lapping results, lightly tap the valve
seat while rotating the valve back and forth be-
tween your hand.
D Apply a fine lapping compound to the valve
face and repeat the above steps.
Make sure to clean off all compound from the
valve face and valve seat after every lapping
operation.
D Apply Mechanic’s blueing dye (Dykem)
b
to
the valve face.
D Install the valve into the cylinder head.
D Press the valve through the valve guide and
onto the valve seat to make a clear pattern.
D Measure the valve seat width
c
again.
EB404032
VALVES AND VALVE SPRINGS
INSTALLATION
1. Deburr:
SValve stem end
Use an oil stone to smooth the stem end.
2. Apply:
SMolybdenum disulfide oil
(onto the valve stem
3
and oil seal
2
)
Molybdenum disulfide oil
3. Install:
SValve spring seat
1
SValve stem seal
2
SValve
3
(into the cylinder head)
SValve spring (inner)
4
SValve spring (outer)
5
SSpring retainer
6
Install the valve spring with the larger pitch
a
facing upwards.
b
Smaller pitch