Honda CRF450RX 2020 Owner's Manual & Competition Handbook page 89

Valve Clearance
Camshaft Installation
1. Lift the rocker arms (1) up and install the
newly selected shims (2) on the valve spring
retainers (3).
Do not let the shims fall into the crankcase.
(3)
(1)
(2)
(3)
(1) rocker arms (3) valve spring retainers
(2) shims
84
Servicing Your Honda
2. Check the operation of the plunger (4) by
turning the decompressor weight (5) with your
finger. The plunger should be retracted and
protruded smoothly.
(5)
(4)
(2)
(1) (3)
(4) plunger
(5) decompressor weight
If the operation is not smooth, refer to an official
Honda Service Manual (page 186) for
decompressor disassembly or see your dealer.
3. Make sure the piston is at TDC on the
compression stroke (page 80).
4. Apply molybdenum disulfide oil (a mixture of
1/2 engine oil and 1/2 molybdenum disulfide
grease containing more than 3% molybdenum
disulfide additive Moly Paste 77) to the
following parts.
– camshaft cam lobes
– plunger whole surface
5. Install the camshaft (6) onto the cylinder head
with the decompressor weight (5) facing up as
illustrated below.
6. Install the cam chain (7) over the cam sprocket
(8).
While holding the left camshaft bearing (9) to
the left fully, install the camshaft (6) onto the
cylinder head (10) and slide the left camshaft
bearing to the right fully.
(7)
(9)
(8)
(5) decompressor weight (8) cam sprocket
(6) camshaft (9) left camshaft bearing
(7) cam chain (10) cylinder head
(6)
(10)
(5)