Honda NX250 1989, Manuals

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2 1 . TROUBLESHOOTING
ENGINE DOES NOT START OR IS
HARD TO START
ENGINE LACKS POWER
POOR PERFORMANCE AT LOW
21-1 AND IDLE SPEEDS 21-3
21-2 POOR PERFORMANCE AT HIGH SPEED 21-4
ENGINE DOES NOT START OR IS HARD TO START
1. Check to see if fuel is getting to the NOT GETTING TO CARBURETOR -
carburetor.
GETTING TO CARBURETOR
2. Try spark test.
SPARKS JUMP
3. Test cylinder compression
COMPRESSION NORMAL
4. Start by following normal starting
procedure.
ENGINE DOES NOT FIRE
5. Remove spark plug.
DRY
6. Pour small amount of fuel into
cylinder from the spark plug hole,
install plug and try to start engine
WEAK OR NO SPARK-
LOW COMPRESSION
ENGINE FIRES BUT SOON STOPS
WET PLUG
ENGINE STARTS BUT
STOPS SOON
ENGINE DOES NOT START
Probable Cause
*• Clogged fuel tube or fuel strainer
• Clogged float valve
• Clogged fuel tank cap breather tube
- • • Faulty spark plug
• Fouled spark plug
• Faulty CDI unit
• Broken or shorted spark plug wire
• Faulty alternator
• Broken or shorted ignition coil
• Faulty engine stop switch
• Faulty pulse generator
• Poorly connected, broken or short-
ed wires
•• Insufficient valve clearance
• Valve stuck open
• Worn cylinder and piston
• Damaged cylinder head gasket
• Improper valve timing
• Improper valve and seat contact
• Seized valve
*• Choke excessively open
• Carburetor pilot screw excessively
closed
• Air leaking past intake pipe
• Improper ignition timing
(CDI unit or pulse generator faulty)
• • Carburetor flooded
• Carburetor choke excessively
closed
• Throttle valve excessively open
• Clogged air cleaner element
• Clogged carburetor
• Faulty carburetor
• Restricted fuel line
-• Incorrect ignition timing
21-1