Troubleshooting - Honda 2005 CRF450R Owner's Manual

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 HAND 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
procedure
STOPS
ENGINE DOES
NOT FIRE
5. Removed and WET PLUG
inspect spark plug
DRY
6. START WITH CHOKE ON
POOR PERFORMANCE AT LOW AND UNSTABLE
IDLE SPEED
CHECK
1. Check if air
cleaner is over-
oiled (P.44)
CORRECT
POSSIBLE CAUSES
• No fuel in fuel tank
2. Check if the insulator
• Clogged fuel tube or
is leaking
fuel strainer screen
(p.34)
NOT LEAKING
• Sticking float valve*
• Clogged fuel fill cap
breather tube (p.34)
3. Check carburetor
pilot screw
• Faulty spark plug (p.54)
adjustment (P.126)
• Fouled spark plug (p.54)
• Faulty ignition control
CORRECT
module*
• Broken or shorted spark
plug wire
• Faulty exciter coil
4. Check carburetor
• Broken or shorted ignition
jets and accelerator
coil
pump for clogs
• Faulty engine stop button
• Loose or disconnected
NOT CLOGGED
ignition system wires
• Faulty ignition pulse
generator*
5. Try spark test
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
• Improper ignition timing
6. Check the throttle
(Faulty ignition coil or
position sensor*
ignition pulse generator)*
• Fuel contaminated CORRECT
• Improper hot start
operation (p. 53)
7. Test cylinder
• Carburetor flooded
compression.
• Choke closed
• Throttle valve open CORRECT
• Air cleaner dirty (p. 43)
POSSIBLE CAUSES
• Over-oiled air cleaner.
INCORRECT
LEAKING
• Loose insulator clamp
• Damaged insulator
INCORRECT • Fuel-air mixture too
lean (Turn the pilot
screw out) (P.126)
• Fuel-air mixture too rich
(Turn the pilot screw in)
(P.126)
CLOGGED • Contaminants in the
fuel
• Not cleaned frequently
enough (P.121)
WAKE OR
• Faulty, carbon or wet
INTERMITTENT fouled spark pulg (P .128)
• Faulty ignition control
SPARK
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 button
INCORRECT • Faulty throttle position
sensor*
LOW • Ring worn
• Cylinder worn or
damaged*
• Piston worn or
damaged*
• Head gasket not
sealing
• Valve stick open

Troubleshooting

POOR PERFORMANCE AT HIGH SPEED
CHECK
1. Disconnect fuel FUEL FLOW
line at carburetor RESTRICTED
and check for
clogging (P.34)
UNRESTRICTED
FUEL FLOW
2. Remove air
DIRTY
cleaner (P.43)
AIR CLEANER
NOT DIRTY
3. Install a larger CONDITION
carburetor main WORSE
jet (P.124)
CORRECT
4. Check carbureator CLOGGED
jets for clogging
NOT CLOGGED
5. Check valve INCORRECT
timing
CORRECT
6. Try spark test WEAK OR
INTERMITTENT
GOOD SPARK
SPARK
LOW
7. Test cylinder
compression.
CORRECT
POSSIBLE CAUSES
• 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.126)
• Contaminants in
the fuel
• Cam sprocket not
installed properly
• Faulty, carbon or wet
fouled spark pulg
(P.128)
• 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 button
• Ring worn
• Cylinder worn or
damaged
• Piston worn or damaged
• Head gasket not sealing
• Improper valve timing
• Valve stick open
137
Tips