Troubleshooting - Honda CRF250X Owner's Manual & Competition Handbook

250X_140-168.qxd 08.7.3 10:16 ページ144

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 Shop Manual are followed by an asterisk
(*).
ENGINE DOES NOT START OR IS HARD TO START
CHECK POSSIBLE CAUSES
1. Check the fuel NOT REACHING • No fuel in fuel tank
flow to carburetor • Clogged fuel line or fuel
CARBURETOR
filter (P. 41, 42)
REACHING
• Sticking float valve
CARBURETOR
• Clogged fuel fill cap
breather tube (P. 41)
2. Try spark test • Faulty spark plug (P. 61)
WEAK OR NO
• Fouled spark plug
SPARK
GOOD SPARK
(P. 61)
• Faulty ignition control
module
• Faulty exciter coil
• Broken or shorted direct
ignition coil
• Faulty engine stop button
• Loose or disconnected
ignition system wires
• Faulty ignition pulse
generator
3. Test cylinder LOW
• Valve stuck open
compression * • Worn cylinder and piston
ring
CORRECT
• Leaking/damaged
cylinder head gasket
• Improper valve timing
• Faulty decomp system
• Seized valve
4. Start by following ENGINE STARTS
normal starting BUT SOON • Improper choke operation
procedure • Pilot screw incorrectly
STOPS
adjusted
ENGINE DOES
• Insulator leaking
NOT FIRE • Improper ignition timing
(Faulty direct ignition
coil or ignition pulse
generator)
• Fuel contaminated
• Improper hot start
operation (P. 60)
5. Removed and WET PLUG
• Carburetor flooded
inspect spark plug • Choke opened
• Throttle valve open
DRY
• Air cleaner dirty (P. 51)
6. START WITH CHOKE ON
144
Tips
POOR PERFORMANCE AT LOW AND UNSTABLE
IDLE SPEED
CHECK
INCORRECT
1. Check if air
cleaner is over-
oiled (P. 51)
CORRECT
2. Check if the intake LEAKING
tube is leaking
*
NOT LEAKING
3. Check carbureator INCORRECT
pilot screw
adjustment *
CORRECT
*
4. Check carburetor CLOGGED
jets and accelerator
pump for clogs
NOT CLOGGED
*
5. Try spark test WEAK OR
INTERMITTENT
*
GOOD SPARK
SPARK
*
*
6. Check the throttle INCORRECT
position sensor
*
CORRECT
*
LOW
7. Test cylinder
compression *
CORRECT
POOR PERFORMANCE AT HIGH SPEED
CHECK
1. Disconnect fuel FUEL FLOW
POSSIBLE CAUSES
line at carburetor RESTRICTED
• Over-oiled air cleaner
and check for
clogging (P. 41)
UNRESTRICTED
FUEL FLOW
• Loose insulator clamp
• Damaged insulator
2. Remove air DIRTY
cleaner (P. 51)
• Fuel-air mixture too AIR CLEANER
NOT DIRTY
lean (Turn the pilot
screw out) *
• Fuel-air mixture too rich
(Turn the pilot screw in) *
3. Check carburetor CLOGGED
jets for clogging
NOT CLOGGED
• Contaminants in the
fuel
• Not cleaned frequently
enough (P. 131)
4. Check valve INCORRECT
timing
CORRECT
• Faulty, carbon or wet
fouled spark plug (P. 61)
• Faulty ignition control
5. Try spark test WEAK OR
module *
INTERMITTENT
GOOD SPARK
• Faulty alternator *
SPARK
• Faulty direct ignition coil
*
• Broken or shorted
direct ignition coil wire
• Faulty ignition pulse
generator *
• Faulty throttle position
sensor *
6. Test cylinder LOW
• Ring worn
compression *
• Cylinder worn or
damaged *
CORRECT
• Piston worn or
damaged *
• Head gasket not
sealing
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 plug
(P. 61)
• Faulty ignition control
module *
• Faulty alternator *
• Faulty direct ignition coil *
• Broken or shorted
direct ignition coil 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