Honda CRF450X 2017 Owner's Manual & Competition Handbook page 75

Valve Clearance
Shim Selection
1. Clean the shim contact area in the valve lifter
(1) with compressed air.
(1) valve lifter
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Servicing Your Honda
17 CRF450X̲31MEY710.indb 70 17 CRF450X̲31MEY710.indb 70
2. Measure the shim thickness with a
micrometer and record it.
Seventy-three different thickness shims (2)
are available from the thinnest (1.200 mm
thickness) shim to the thickest (3.000 mm
thickness) in intervals of 0.025 mm.
(1)
(2) shim
3. Calculate the new shim thickness using the
equation below.
A = (B – C) + D
A: New shim thickness
B: Recorded valve clearance
C: Specified valve clearance
(2)
D: Old shim thickness
• Make sure of the correct shim thickness by
measuring the shim with a micrometer.
• Reface the intake valve seat if carbon deposits
result in a calculated dimension of over
2.450 mm.
Reface the exhaust valve seat if carbon
deposits result in a calculated dimension of
over 3.000 mm.
180
1.80 mm
182 185 188
1.825 mm 1.85 mm 1.875 mm
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