Shim Selection - Honda CRF250R Owner's Manual

Shim Selection

1. Clean the valve shim contact area in the valve
lifter (1) with compressed air.
(1)
(1) valve lifter
2. Measure the shim thickness with a micrometer
and record it.
Sixty-nine different shims (2) are available in
0.025 mm thickness intervals, from 1.200 mm
(the thinnest) to 2.900 mm (the thickest).
(2)
(2) shim
Valve Clearance
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
D: Old shim thickness
• Make sure of the correct shim thickness by
measuring the shim with a micrometer.
• Reface the exhaust valve seat if carbon deposits
result in a calculated dimension of over 2.900
mm.
NOTICE
Do not lap the intake valves. They are titanium and
have a thin oxide coating. Lapping will damage
this coating.
If a calculated dimension is out of specifications,
have your motorcycle inspected by your dealer.
1.80 mm 1.825 mm 1.85 mm 1.875 mm
Servicing Your Honda
71