Honda CRF450X 2006 Service Manual

CYLINDER HEADIVALVES
CYLINDER HEAD INSPECTION
CYLINDER HEAD
Use care not to
SCf8fcil the
combustion
ctl8mber or head
gasket surface.
9-28
Disassemble the cyl inder head (page 9-27),
Remove
the ca r bon deposits from the comb us ti on
chamber and ex haust port.
Check th e spark plug hole and valve areas for
cracks.
Check the cylinde r head for warpage with a str aight
edge and feeler gauge.
SERVICE LIMIT : 0.05 mm (0 .002 in)
VALVE SPRING
Check the va lve springs for fatigue or damage.
Measure the free length of the intake and exhaust
valve springs.
SERVICE LIMITS :
IN: 39 .7 mm (1.56 in)
EX : 41.9 mm (1 .65 in)
Replace the springs if they are shorter than the ser-
vice limit
s.
VALVEIVALVE GUIDE
Inspect each valve for out - af- round, burns,
sc ratches or abnor ma l stem wear.
Check the valve movement in the guide.
Measure and record the valve st em 0.0.
STANDARD:
IN: 5.475 - 5.490 mm (0 .2156 - 0.2161 in)
EX: 4 .9 65 - 4.980 mm (0.1955 - 0.1961 in)
SERVICE LIMIT:
EX: 4. 96 mm (0.195 in)
\ ~
EXH AUST
VA LVE SPRING
...
INTAKE VALVE
•

Honda CRF450X 2006 Specifications

General

Displacement	449 cc
Bore x Stroke	96.0 mm x 62.1 mm
Compression Ratio	12.0:1
Transmission	5-speed
Final Drive	#520 chain; 13T/51T
Front Brake	Single 240 mm disc with twin-piston caliper
Rear Brake	Single 240 mm disc
Front Tire	80/100-21
Rear Tire	110/100-18
Wheelbase	58.3 inches
Engine Type	Liquid-cooled single-cylinder four-stroke
Fuel System	Keihin 40mm flat-slide carburetor
Valve Train	Unicam, 4-valve
Induction	Keihin 40 mm flat-slide carburetor with Throttle Position Sensor (TPS)
Ignition	CD with electronic advance
Front Suspension	47mm inverted Showa cartridge fork with 16-position rebound and 16-position compression damping adjustability; 12.4 inches travel
Rear Suspension	Pro-Link Showa single shock with spring preload, 17-position rebound damping adjustability, and compression damping adjustment separated into low-speed (13 positions) and high-speed (3.5 turns); 12.4 inches travel