Troubleshooting; Poor Performance At Low And Unstable Idle Speeds; Poor Performance At High Speed - Honda CRF450R Owner's Manual

12. TROUBLESHOOTING

NOTE:
• The items that are serviceable using this Manual are
followed by the page number reference in paren-
thesis. The items that require use of the Honda Ser-
vice Manual are followed by an asterisk.
POOR PERFORMANCE AT LOW AND UNSTABLE
IDLE SPEED
CHECK
1. Check if air INCORRECT
cleaner is over-
oiled (P-27)
CORRECT
2. Check if the intake
LEAKING
tube is leaking
NOT LEAKING
3. Check carbureator INCORRECT
pilot screw
adjustment (P-69)
CORRECT
4. Check carburetor CLOGGED
jets and accelerator
pump for clogs
NOT CLOGGED
5. Try spark test WAKE OR
INTERMITTENT
GOOD SPARK
SPARK
6. Check for LOW
low compression.
CORRECT

POOR PERFORMANCE AT HIGH SPEED

CHECK
1. Disconnect fuel
line at carburetor
and check for
clogging (P-48)
UNRESTRICTED
FUEL FLOW
POSSIBLE CAUSES
(1) Over-oiled air
cleaner.
2. Remove air
cleaner (P-27)
AIR FILTER
(1) Loose insulator NOT DIRTY
clamp
(2) Damaged insulator
3. Install a larger
carburetor main
jet (p-67)
(1) Fuel-air mixture too
CORRECT
lean (Turn the pilot
screw out) (P-69)
(2) Fuel-air mixture too
rich (Turn the pilot
4. Check carbureator
screw in) (P-69)
jets for clogging
NOT CLOGGED
(1) Contaminants in the
fuel
(2) Not cleaned
5. Check valve
frequently enough
timing
(P-62)
CORRECT
(1) Faulty, carbon or
wet fouled spark
pulg (P-25) 6. Try spark test
(2) Faulty ignition
GOOD SPARK
control module*
(3) Faulty alternator*
(4) Faulty ignition coil*
(5) Broken or shorted
spark plug wire.
(6) Faulty ignition
pulse generator*.
(1) Ring worn
(2) Cylinder worn or
damaged
7. Check for
(3) Piston worn or
low compression.
damaged
CORRECT
(4) Head gasket not
sealing
POSSIBLE CAUSES
FUEL FLOW (1) Lack of fuel in tank
RESTRICTED (P-2)
(2) Clogged fuel line
(P-48)
(3) Clogged fuel fill
cap breather tube
(P-2)
(4) Clogged fuel valve
(P-48)
(5) Clogged fuel filter
(P-48)
DIRTY (1) Not cleaned
frequently enough
(P-27)
CONDITION
(1) Jet size wrong, rejet
WORSE
in the opposite
direction (P-67)
CLOGGED (1) Contaminants in
the fuel
INCORRECT (1) Cam sprocket not
installed properly
WEAK OR
(1) Faulty, carbon or wet
INTERMITTENT fouled spark pulg
(P-25)
SPARK
(2) Faulty ignition control
module*
(3) Faulty alternator*
(4) Faulty ignition coil*
(5) Broken or shorted
spark plug wire.
(6) Faulty ignition pulse
generator*.
(1) Ring worn
LOW
(2) Cylinder worn or
damaged
(3) Piston worn or
damaged
(4) Head gasket not
sealing
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