Checking The Valve Seats - Yamaha MT-03 Service Manual

3. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
4. Check:
• Valve face
Pitting/wear •Grind the valve face.
• Valve stem end
Mushroom shape or diameter larger than
the body of the valve stem
valve.
5. Measure:
• Valve margin thickness "a"
Out of specification
Valve margin thickness
0.80-1.20 mm
(0.0315-0.0472 in)
6. Measure:
• Valve stem runout
Out of specification
NOTE:
• When installing a new valve, always replace
the valve guide.
• If the valve is removed or replaced, always re-
place the valve stem seal.
Valve stem runout
0.010 mm (0.0004 in)
Replace the
Replace the valve.
Replace the valve.
VALVES AND VALVE SPRINGS
EAS00240

CHECKING THE VALVE SEATS

The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
2. Check:
• Valve seat
Pitting/wear
3. Measure:
• Valve seat width "a"
Out of specification
head.
Valve seat width
Intake
1.00-1.20 mm
(0.0394-0.0472 in)
Exhaust
1.00-1.20 mm
(0.0394-0.0472 in)
a. Apply Mechanic's blueing dye (Dykem) onto
the valve face.
b. Install the valve into the cylinder head.
c. Press the valve through the valve guide and
onto the valve seat to make a clear impres-
sion.
d. Measure the valve seat width.
NOTE:
Where the valve seat and valve face contacted
one another, the blueing will have been re-
moved.
5-23
Replace the cylinder head.
Replace the cylinder