Checking The Valve Seat - Yamaha YBR250 2007 Service Manual

VALVES AND VALVE SPRINGS
6. Measure:
NOTE:
•
•

CHECKING THE VALVE SEAT

The following procedure applies to all of the valves
and valve seats.
1. Eliminate:
2. Check:
3. Measure:
a
a. Apply Mechanic's blueing dye (Dykem) b onto
b
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide and
d. Measure the valve seat width.
NOTE:
Where the valve seat and valve face contacted
one another, the blueing will have been removed.
5-26
• stem runout
Out of specification --> Replace the valve.
When installing a new valve, always replace
the valve guide.
If the valve is removed or replaced, replace
the valve stem oil seal.
Runout limit
0.030 mm (0.0012 in)
• carbon deposits
• valve seat
Pitting/Wear --> Replace the cylinder head.
• valve seat width a
Out of specification --> Replace the cylinder
head.
Valve seat width
Intake
0.90 ~ 1.10mm (0.03 ~ 0.04 in)
Exhaust
0.90 ~ 1.10mm (0.03 ~ 0.04 in)
the valve face.
onto the valve seat to make a clear impression.
ENG