Checking The Valve Springs; Installing The Valves - Yamaha MBK X-MAX 300 2017 Service Manual

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, and then
clean off all of the lapping compound.
TIP
For the best lapping results, lightly tap the valve
seat while rotating the valve back and forth be-
tween your hands.
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 blue layout fluid "b" 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.
VALVES AND VALVE SPRINGS
j. Measure the valve seat width again. If the
valve seat width is out of specification, re-
face and lap the valve seat.
EAS30286

CHECKING THE VALVE SPRINGS

The following procedure applies to all of the
valve springs.
1. Measure:
• Valve spring free length "a"
Out of specification → Replace the valve
spring.
Free length (intake)
35.87 mm (1.41 in)
Limit
34.07 mm (1.34 in)
Free length (exhaust)
35.87 mm (1.41 in)
Limit
34.07 mm (1.34 in)
EAS30288

INSTALLING THE VALVES

The following procedure applies to all of the
valves and related components.
1. Deburr:
• Valve stem end
(with an oil stone)
2. Lubricate:
• Valve stem "1"
Recommended lubricant
Molybdenum disulfide oil
5-30