Yamaha YZF-R1, Service Manual

Page: 115 / 808

PERIODIC MAINTENANCE
3-8
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 pad
so that they can be installed in the correct
place.
b. Calculate the difference between the
specified valve clearance and the mea-
sured valve clearance.
Example:
Specified valve clearance = 0.09–0.17
mm (0.004–0.007 in)
Measured valve clearance = 0.20 mm
(0.008 in)
0.20 mm (0.008 in) - 0.17 mm (0.007 in) =
0.03 mm (0.001 in)
c. Check the thickness of the current valve
pad.
TIP
• The letter and number “a” marked on the valve
pad indicate the valve pad thickness.
• The letter A marked on the valve pad indicates
1 mm (0.04 in), while B indicates 2 mm (0.08
in).
• The number marked on the valve pad indicates
hundredths of millimeters.
Example:
If the valve pad is marked “A60”, the pad
thickness is 1.60 mm (0.063 in).
If the valve pad is marked “B30”, the pad
thickness is 2.30 mm (0.091 in).
d. Calculate the sum of the values obtained
in steps (b) and (c) to determine the re-
quired valve pad thickness and the valve
pad number.
Example:
1.60 mm (0.063 in) + 0.03 mm (0.001 in) =
1.63 mm (0.064 in)
The valve pad number is A63.
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.
Example:
Valve pad number = A63
Rounded value = A65
New valve pad number = A65
f. Install the new valve pad “3” and then,
push the rocker arm “1” down.
TIP
• Lubricate the valve pad with molybdenum di-
sulfide oil.
• Install the valve pad in the correct place.
g. Install the exhaust and intake camshafts,
timing chain and camshaft caps.
1
2
a
G0 8888 6
Last digit Rounded value
0, 1, 2 0
3, 4, 5, 6 5
7, 8, 9 10
Valve pad range No. A60–A99, B00–B40
Valve pad thickness
1.60–2.40 mm
(0.0630–0.0944 in)
Available valve pads
17 thicknesses in 0.05
mm (0.002 in) incre-
ments
3
1