Troubleshooting - Honda CRF450X 2017 Owner's Manual & Competition Handbook

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 *
CORRECT
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
152
Tips
17 CRF450X̲31MEY710.indb 152 17 CRF450X̲31MEY710.indb 152
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 line or
connecting tube
fuel filter (P.42)
and/or insulator
• Sticking float valve
*
is leaking
• Clogged fuel fill cap
NOT LEAKING
breather tube (P.41)
• Faulty spark plug (P.61)
3. Check carburetor
• Fouled spark plug (P.61)
pilot screw
• Faulty ignition control
*
adjustment
module *
• Broken or shorted
CORRECT
spark plug wire
• Faulty exciter coil
*
• Broken or shorted 4. Check carburetor
ignition coil
jets and accelerator
• Faulty engine stop pump for clogs
button
NOT CLOGGED
• Loose or disconnected
ignition system wires
• Faulty ignition pulse
5. Try spark test *
generator
*
GOOD SPARK
• Valve stuck open
• Worn cylinder and
piston ring
*
• Leaking/damaged
cylinder head gasket
• Improper valve timing
*
• 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. Test cylinder
• Carburetor flooded
compression *
• Choke closed
• Throttle valve open
CORRECT
• Air cleaner dirty (P.51)
POSSIBLE CAUSES
INCORRECT • Over-oiled air cleaner
LEAKING • Loose connecting
tube and/or insulator
band
• Damaged connecting
tube and/or insulator
INCORRECT • Improper pilot screw
adjustment *
CLOGGED • Contaminants in the fuel
• Not cleaned
frequently enough
(P.137)
WEAK OR
• Faulty, carbon or wet
INTERMITTENT
fouled spark plug (P.61)
SPARK • Faulty ignition control
module *
• Faulty exciter coil *
• Faulty ignition coil *
• Broken or shorted
spark plug wire
• Faulty ignition pulse
generator *
• Loose or disconnected
ignition system wires
• Faulty engine stop
button
INCORRECT • Faulty throttle position
sensor *
LOW • Ring worn
• Cylinder worn or
damaged *
• Piston worn or
damaged *
• Head gasket not
sealing
• Valve stuck open
POOR PERFORMANCE AT HIGH SPEED
CHECK POSSIBLE CAUSES
• Lack of fuel in tank
1. Disconnect fuel FUEL FLOW
(P.41)
line at carburetor RESTRICTED
• Clogged fuel line
and check for
clogging (P.41) (P.41)
• Clogged fuel fill
UNRESTRICTED
cap breather tube
FUEL FLOW
(P.41)
• Clogged fuel valve
(P.41)
• Clogged fuel filter
(P.42)
2. Remove air • Not cleaned
DIRTY
cleaner (P.51) frequently enough
(P.51)
AIR CLEANER
NOT DIRTY
3. Check carburetor CLOGGED
• Contaminants in
jets for clogging
the fuel
NOT CLOGGED
4. Check valve INCORRECT • Cam sprocket not
timing installed properly
CORRECT
5. Try spark test * WEAK OR
• Faulty, carbon or wet
INTERMITTENT
fouled spark plug
GOOD SPARK
SPARK (P.61)
• Faulty ignition control
module
• Faulty exciter coil
• Faulty ignition coil
• Broken or shorted
spark plug wire
• Faulty ignition pulse
generator
• Loose or
disconnected
ignition system wires
• Faulty engine stop
button
LOW
6. Test cylinder • Ring worn
• Cylinder worn or
compression *
damaged
CORRECT
• Piston worn or
damaged
• Head gasket not
sealing
• Improper valve
timing
• Valve stuck open
*
*
*
*
*
*
*
2016/06/08 11:46:27 2016/06/08 11:46:27