ENG
VALVES AND VALVE SPRINGS
4. Lap:
• valve face
• valve seat
After replacing the cylinder head or replacing the
valve and valve guide, the valve seat and valve
face should be lapped.
NOTE:
a. Apply a coarse lapping compound
a
to the
valve face.
b. Apply molybdenum disulfide oil onto the valve
stem.
c. Install the valve into the cylinder head.
d. Turn the valve until the valve face and valve
seat are evenly polished, then clean off all of
the lapping compound.
e. Apply a fine lapping compound to the valve
face and repeat the above steps.
f.
After every lapping procedure, be sure to clean
off all of the lapping compound from the valve
face and valve seat.
g. Apply Mechanic’s blueing dye (Dykem)
a
onto
the valve face.
h. Install the valve into the cylinder head.
i.
Press the valve through the valve guide and
onto the valve seat to make a clear
impression.
j.
Measure the valve seat width again. If the
valve seat width is out of specification, reface
and lap the valve seat.
TTTTTTTTTTTTTTTTTTTTTTTTTTTT
T
T
TTTTTT
T
T
T
T
Do not let the lapping compound enter the gap
between the stem and the valve guide.
CAUTION:
Valve polisher
1
1
1
1
1
90890-04101
T TT
T TT
T TT
T TT
T TT
T TT
T TT
T TT
T TT
T
T
T
T TT
T TT
T
T
T
T
a
1
a
For the best lapping results, lightly tap the valve
seat while rotating the valve back and forth between
your hands.
NOTE:
5-27
Summary of Contents for YBR250 2007
Page 1: ...YBR250 SERVICE MANUAL 5D1 F8197 E0 2007 ...
Page 2: ......
Page 359: ...YAMAHA MOTOR DA AMAZÔNIA LTDA ...
