144 Tips
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
(*).
POOR PERFORMANCE AT LOW AND UNSTABLE
IDLE SPEED
CHECK POSSIBLE CAUSES
1. Check if air
cleaner is over-
oiled (P. 51)
CORRECT
INCORRECT
INCORRECT
LEAKING
CLOGGED
WEAK OR
INTERMITTENT
SPARK
CORRECT
NOT LEAKING
NOT CLOGGED
GOOD SPARK
2. Check if the intake
tube is leaking
3. Check carbureator
pilot screw
adjustment
*
4. Check carburetor
jets and accelerator
pump for clogs
5. Try spark test
LOW
CORRECT
7. Test cylinder
compression
*
INCORRECT
CORRECT
6. Check the throttle
position sensor
*
• Over-oiled air cleaner
• Loose insulator clamp
• Damaged insulator
• Fuel-air mixture too
lean (Turn the pilot
screw out)
*
• Fuel-air mixture too rich
(Turn the pilot screw in)
*
• Contaminants in the
fuel
• Not cleaned frequently
enough (P. 131)
•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
*
•Faulty throttle position
sensor
*
• Ring worn
• Cylinder worn or
damaged
*
• Piston worn or
damaged
*
• Head gasket not
sealing
POOR PERFORMANCE AT HIGH SPEED
CHECK POSSIBLE CAUSES
1. Disconnect fuel
line at carburetor
and check for
clogging (P. 41)
UNRESTRICTED
FUEL FLOW
FUEL FLOW
RESTRICTED
DIRTY
2. Remove air
cleaner (P. 51)
AIR CLEANER
NOT DIRTY
CLOGGED
INCORRECT
LOW
WEAK OR
INTERMITTENT
SPARK
NOT CLOGGED
CORRECT
CORRECT
GOOD SPARK
3. Check carburetor
jets for clogging
4. Check valve
timing
5. Try spark test
6. Test cylinder
compression
*
• 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
ENGINE DOES NOT START OR IS HARD TO START
CHECK POSSIBLE CAUSES
4. Start by following
normal starting
procedure
ENGINE DOES
NOT FIRE
ENGINE STARTS
BUT SOON
STOPS
2. Try spark test
GOOD SPARK
WEAK OR NO
SPARK
NOT REACHING
CARBURETOR
3. Test cylinder
compression
*
CORRECT
LOW
1. Check the fuel
flow to carburetor
REACHING
CARBURETOR
5. Removed and
inspect spark plug
6. START WITH CHOKE ON
DRY
WET PLUG
• No fuel in fuel tank
• Clogged fuel line or fuel
filter (P. 41, 42)
• Sticking float valve
*
• Clogged fuel fill cap
breather tube (P. 41)
• Faulty spark plug (P. 61)
• Fouled spark plug
(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
*
• Valve stuck open
• Worn cylinder and piston
ring
*
• Leaking/damaged
cylinder head gasket
• Improper valve timing
*
• Faulty decomp system
• Seized valve
• Improper choke operation
• Pilot screw incorrectly
adjusted
*
• Insulator leaking
• Improper ignition timing
(Faulty direct ignition
coil or ignition pulse
generator)
*
• Fuel contaminated
• Improper hot start
operation (P. 60)
• Carburetor flooded
• Choke opened
• Throttle valve open
• Air cleaner dirty (P. 51)
250X_140-168.qxd 08.7.3 10:16 ページ144
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