Honda CRF450R User Manual

Troubleshooting
Tips 139
The items that are serviceable using this Manual
are followed by the page number reference in
parenthesis. The items that require use of the
Honda Service Manual are followed by an
asterisk.
POOR PERFORMANCE AT LOW AND UNSTABLE
IDLE SPEED
CHECK POSSIBLE CAUSES
1. Check if air
cleaner is over-
oiled (P-43)
CORRECT
INCORRECT
INCORRECT
LEAKING
CLOGGED
WAKE OR
INTERMITTENT
SPARK
CORRECT
NOT LEAKING
NOT CLOGGED
GOOD SPARK
2. Check if the intake
tube is leaking
3. Check carburetor
pilot screw
adjustment (P-128)
4. Check carburetor
jets and accelerator
pump for clogs
5. Try spark test
LOW
CORRECT
6. Check for
low compression.
• Over-oiled air cleaner.
• Loose insulator clamp
• Damaged insulator
• Fuel-air mixture too
lean (Turn the pilot
screw out) (P-128)
• Fuel-air mixture too rich
(Turn the pilot screw in)
(P-128)
• Contaminants in the
fuel
• Not cleaned frequently
enough (P-123)
• Faulty, carbon or wet
fouled spark pulg (P-130)
• Faulty ignition control
module*
• Faulty alternator*
• Faulty ignition coil*
• Broken or shorted
spark plug wire.
• Faulty ignition pulse
generator*.
• Loose or disconnected
ignition system wires
• Faulty engine stop switch
• Ring worn
• Cylinder worn or
damaged
• Piston worn or
damaged
• Head gasket not
sealing
• Valve stick open
POOR PERFORMANCE AT HIGH SPEED
CHECK POSSIBLE CAUSES
1. Disconnect fuel
line at carburetor
and check for
clogging (P-34)
UNRESTRICTED
FUEL FLOW
FUEL FLOW
RESTRICTED
CLOGGED
DIRTY
INCORRECT
LOW
WEAK OR
INTERMITTENT
SPARK
NOT CLOGGED
CORRECT
CORRECT
GOOD SPARK
2. Remove air
cleaner (P-43)
4. Check carbureator
jets for clogging
5. Check valve
timing
6. Try spark test
7. Check for
low compression.
AIR FILTER
NOT DIRTY
3. Install a larger
carburetor main
jet (p-126)
CORRECT
CONDITION
WORSE
• Lack of fuel in tank
(P-34)
• Clogged fuel line
(P-34)
• Clogged fuel fill
cap breather tube
(P-34)
• Clogged fuel valve
(P-34)
• Clogged fuel filter
(P-35)
• Not cleaned
frequently enough
(P-43)
• Jet size wrong, rejet
in the opposite
direction (P-128)
• Contaminants in
the fuel
• Cam sprocket not
installed properly
• Faulty, carbon or wet
fouled spark pulg
(P-130)
• Faulty ignition control
module*
• Faulty alternator*
• Faulty ignition coil*
• Broken or shorted
spark plug wire.
• Faulty ignition pulse
generator*.
• Loose or disconnected
ignition system wires
• Faulty engine stop switch
• Ring worn
• Cylinder worn or
damaged
• Piston worn or damaged
• Head gasket not sealing
• Improper valve timing
• Valve stick open

Honda CRF450R Specifications

General

Brand	Honda
Model	CRF450R
Category	Motorcycle
Language	English