Honda CRF450R 2007 Service Manual

CYLINDER HEADIVALVES
TROUBLESHOOTING
• Engine top - end problems usually affect engine p erformance. These problems can be diagn osed by a comp ression test
or by tracing top-end noise with a sounding rod stethoscope.
• If the performance is poor at low speeds, check for wh i te s moke in the crankcase breather hose. If the hose is smoky,
check
for a seized piston ri ng .
Compression too l ow , hard starting or poor performance at low speed
• Valves:
- Incorrect valve adjustment
- Burned or bent valves
- Incorrect valve timing
- Weak valve spring
- Uneven
valve seating
- Valve stuck
open
• Cylinder head:
- leaking or damaged cylinder head gasket
- Warped or cracked cy linder head
• loose spark plug
• Faulty cylinder. piston or piston rings
• Faulty decomp ressor system
Compression too high
• Excessive carbon bui l d-up in cylinder head or t op of pi ston
Excessive smoke
• Worn valve stem or valve guide
• Damaged stem seal
• Cylinder,
piston or piston rings problem
Excesslv, noi se
• Incorrect valve adjustment
• Sticking valve or broken valve spr ing
• Worn or damaged camshaft
• Worn or damaged valve lifter
• Worn or loose cam chain
• Worn or damaged cam chain tensioner
• Worn cam sprocket teeth
• Cylinder, piston or piston rings problem
Rough idle
•
l ow cylinder compression
9-6
•

Honda CRF450R 2007 Specifications

General

Engine Type	449cc liquid-cooled single-cylinder four-stroke
Bore x Stroke	96.0mm x 62.1mm
Compression Ratio	12.0:1
Transmission	5-speed
Final Drive	#520 chain; 13T/48T
Front Suspension	47mm inverted Showa cartridge fork with 16-position rebound and 16-position compression damping adjustability; 12.4 inches travel
Front Brake	Single 240mm disc with twin-piston caliper
Rear Brake	Single 240mm disc
Front Tire	80/100-21
Rear Tire	110/90-19
Wheelbase	58.3 inches
Seat Height	37.6 inches
Fuel Capacity	1.9 gallons
Induction	Keihin 40mm carburetor
Ignition	CDI
Rear Suspension	Pro-Link Showa single shock with spring preload, 17-position rebound damping adjustability, and compression damping adjustment
Trail	4.6 inches