Yamaha YZF-R1 2012, Service Manual

Page: 127 / 556

PERIODIC MAINTENANCE
3-8
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5. Remove:
• Camshafts
TIP
• Refer to “CAMSHAFTS” on page 5-13.
• When removing the timing chain and cam-
shafts, fasten the timing chain with a wire to
retrieve it if it falls into the crankcase.
6. Adjust:
• Valve clearance
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a. Remove the valve lifter “1” and the valve
pad “2” with a valve lapper “3”.
TIP
• Cover the timing chain opening with a rag to
prevent the valve pad from falling into the
crankcase.
• Make a note of the position of each valve
lifter “1” and valve pad “2” so that they can be
installed in the correct place.
b. Calculate the difference between the speci-
fied valve clearance and the measured
valve clearance.
Example:
Specified valve clearance = 0.11–0.20 mm
(0.0043–0.0079 in)
Measured valve clearance = 0.23 mm
(0.0091 in)
0.23 mm (0.0091 in) - 0.20 mm (0.0079 in)
= 0.03 mm (0.0012 in)
c. Check the thickness of the current valve
pad.
TIP
The thickness “a” of each valve pad is marked
in hundredths of millimeters on the side that
touches the valve lifter.
Example:
If the valve pad is marked “155”, the pad
thickness is 1.55 mm (0.0610 in).
d. Calculate the sum of the values obtained in
steps (b) and (c) to determine the required
valve pad thickness and the valve pad
number.
Example:
1.55 mm (0.0610 in) + 0.03 mm (0.0012 in)
= 1.58 mm (0.0622 in)
The valve pad number is 158.
e. Round off the valve pad number according
to the following table, and then select the
suitable valve pad.
TIP
Refer to the following table for the available
valve pads.
Thickness gauge
90890-03180
Feeler gauge set
YU-26900-9
Valve lapper
90890-04101
Valve lapping tool
YM-A8998
Last digit Rounded value
0, 1, 2 0
3, 4, 5, 6 5
7, 8, 9 10