Yamaha YZ450F Owner's Service Manual page 103

Valve lapper
90890-04101
Valve lapping tool
YM-A8998
1
3
c. Check the number on the originally installed
adjusting pad.
TIP
• The adjusting pad number "a" is indicated on
the top of the adjusting pad.
• For the number on the originally installed ad-
justing pad, convert the last digit of adjusting
pad number as per the below table.
d. Select an adjusting pad with a proper valve
clearance from the adjusting pad selection
table.
2
3-19
TIP
• There are 25 types of adjusting pads, ranging
from 1.20 mm (0.0472 in) to 2.40 mm (0.0945
in), in increments of 0.05 mm (0.0020 in).
• The field where the number on the originally
installed adjusting pad and the measured
valve clearance intersect shows the adjusting
pad number to replace.
Last digit of pad
number
0, 1 or 2
4, 5 or 6
8 or 9
Example:
Pad number = 148
Rounded value = 150
e. Install the new adjusting pads "4" and the
valve lifters "5".
ECA@
NOTICE
Do not twist adjusting pads and valve lifters
forcibly during installation.
TIP
• Apply the engine oil on the valve lifters.
• Apply molybdenum disulfide oil to the valve
stem ends.
• Check that the valve lifters turn smoothly
when rotated with your finger.
• Make sure that valve lifters and adjusting
pads are installed in place.
• Make sure that adjusting pads are installed
with their numbers facing upward.
5
4
f. Install the camshafts (exhaust and intake).
Refer to "CAMSHAFT" on page 5-12.
g. Measure the valve clearance again.
h. If the valve clearance is out of specification,
repeat adjusting the valve clearance until it
is within specification.
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ENGINE
Rounded valve
0
5
10