Honda CRF450R Owner's Manual page 75

Valve Clearance
4. Rotate the crankshaft by turning the primary
drive gear bolt (2) clockwise until the punch
mark (3) on the primary drive gear aligns with
the index mark (4) on the right crankcase
cover. In this position, the piston may either be
on the compression or exhaust stroke.
If the crankshaft passed the punch mark, rotate
the primary drive gear bolt clockwise again
and align the punch mark with the index mark.
The inspection must be made when the piston
is at the top of the compression stroke when
both the intake and exhaust valves are closed.
This condition can be determined by moving
the exhaust rocker arms (5). If they are free, an
indication that the valves are closed and that
the piston is on the compression stroke. If they
are tight and the valves are open, rotate the
primary drive gear bolt 360° and realign the
punch mark with the index mark.
(3) (4)
(2)
(2) primary drive gear bolt (4) index mark
(3) punch mark
68
Servicing Your Honda
(5)
(5) exhaust rocker arms
Valve Clearance Inspection
1. Set the piston at TDC on the compression
stroke (page 67).
2. Measure the intake valve clearance by
inserting a feeler gauge (1) between the valve
lifters and cam lobes (2).
(1)
(2)
(1) feeler gauge
(2) valve lifters and cam lobes
(1)