Troubleshooting - Honda CRF450X 2007 Owner's Manual

Troubleshooting

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.
ENGINE DOES NOT START OR IS HARD TO START
CHECK
1. Check the fuel NOT REACHING
flow to carburetor CARBURETOR
REACHING
CARBURETOR
2. Try spark test
WEAK OR NO
SPARK
GOOD SPARK
3. Test cylinder
LOW
compression
NORMAL
4. Start by following
ENGINE STARTS
normal starting
BUT SOON STOPS
procedure
ENGINE DOES
NOT FIRE
5. Remove and
WET PLUG
inspect spark plug
DRY
6. START WITH CHOKE ON
146
Tips
POOR PERFORMANCE AT LOW AND UNSTABLE
IDLE SPEED
CHECK
1. Check if air
cleaner is over-
oiled (P.51)
CORRECT
POSSIBLE CAUSES
• No fuel in fuel tank
2. Check if the
• Clogged fuel tube or
connecting boot
fuel filter (P.42)
is leaking
• Sticking float valve*
NOT LEAKING
• Clogged fuel fill cap
breather tube (P.41)
• Faulty spark plug (P.61)
3. Check carbureator
• Fouled spark plug (P.61)
pilot screw
• Faulty ignition control
adjustment
module*
• Broken or shorted spark
CORRECT
plug wire
• Faulty exciter coil
• Broken or shorted ignition
coil
4. Check carburetor
• Faulty engine stop button
jets and accelerator
• Loose or disconnected
pump for clogs
ignition system wires
NOT CLOGGED
• Faulty ignition pulse
generator*
• Valve stuck open
5. Try spark test
• Worn cylinder and piston
GOOD SPARK
ring*
• Leaking/damaged
cylinder head gasket
• Improper valve timing*
• Improper decompressor
clearance (P.73)
• Seized valve
• Improper choke operation
• Pilot screw incorrectly
adjusted*
• Insulator leaking
6. Check the throttle
• Improper ignition timing
position sensor*
(Faulty ignition coil or
ignition pulse generator)* CORRECT
• Fuel contaminated
• Improper hot start
operation (P.60)
7. Check for
• Carburetor flooded
low compression.
• Choke closed
• Throttle valve open CORRECT
• Air cleaner dirty (P.51)
POSSIBLE CAUSES
• Over-oiled air cleaner
INCORRECT
LEAKING • Loose insulator clamp
• Damaged insulator
INCORRECT
• Improper pilot screw
adjustment*
CLOGGED
• Contaminants in the
fuel
• Not cleaned frequently
enough (P.133)
WAKE OR
• Faulty, carbon or wet
INTERMITTENT fouled spark pulg (P.61)
SPARK • Faulty ignition control
module*
• Faulty alternator*
• Faulty engine stop
button
• Faulty ignition coil*
• Broken or shorted
spark plug wire
• Faulty ignition pulse
generator*
INCORRECT
• Faulty throttle position
sensor*
LOW
• Ring worn
• Cylinder worn or
damaged*
• Piston worn or
damaged*
• Head gasket not
sealing
POOR PERFORMANCE AT HIGH SPEED
CHECK
FUEL FLOW
1. Disconnect fuel
line at carburetor RESTRICTED
and check for
clogging (P.41)
UNRESTRICTED
FUEL FLOW
2. Remove air
DIRTY
cleaner (P.51)
AIR FILTER
NOT DIRTY
3. Check carbureator CLOGGED
jets for clogging
NOT CLOGGED
4. Check valve INCORRECT
timing
CORRECT
5. Try spark test WEAK OR
INTERMITTENT
GOOD SPARK
SPARK
6. Check for LOW
low compression.
CORRECT
POSSIBLE CAUSES
• Lack of fuel in tank
(P.41)
• Clogged fuel line
(P.41)
• Clogged fuel fill
cap breather tube
(P.41)
• Clogged fuel valve
(P.41)
• Clogged fuel filter
(P.42)
• Not cleaned
frequently enough
(P.51)
• Contaminants in
the fuel
• Cam sprocket not
installed properly
• Faulty, carbon or wet
fouled spark pulg
(P.61)
• Faulty ignition control
module*
• Faulty alternator*
• Faulty engine stop button
• Faulty ignition coil*
• Broken or shorted
spark plug wire
• Faulty ignition pulse
generator*
• Ring worn
• Cylinder worn or
damaged*
• Piston worn or
damaged*
• Head gasket not
sealing