7. TROUBLESHOOTING
Sufficient fuel in tank
Refuel.
• Install a new spark plug, then restart
the engine.
• Check the carburetor for flooding.
• Check the ignition coil air gap (P. 9 -6 ).
Check the valve clearance (P. 3-15),
and then perform the cylinder
compression test. If the cylinder
compression is still too low, perform a
leak down test.
If the air leak down test shows air
leakage, check the following as
determined by the test:
- Valve sticking open (P. 3 -1 5
)
- Valve seat width (P. 1 0- 3 1
)
- Carbon on the valve seat (P. 10-31
)
- Piston ring side clearance (P. 10-25
)
- Piston ring width (P. 1 0 - 25
)
- Piston ring end gap (P. 1 0- 2 5
)
- Piston skirt O.D. (P. 10-24
)
- Cylinder sleeve I.D. (P. 1 0-24
)
Install the spark plug and restart the engine.
No fuel in tank
Dry
Wet
Remove the spark plug and inspect (P. 3- 8 ).
Good spark
No or weak spark
Install a compression gauge in the spark plug hole
(P. 2- 13
) and briskly crank the engine repeatedly until
a stabilized reading is obtained.
Install the spark plug in the plug cap and perform the
spark test (P. 2- 1 3
).
Remove, disassemble, and clean the carburetor
(P. 8- 5
).
Check the choke butterfly with the engine cold.
Choke closed
Confirm the fuel quality. If gasoline is more than 30
days old, the engine may be hard to start.
Fresh fuel
Drain the fuel system, and refill with
fresh gasoline.
Stale fuel
See “CHOKE CONTROL SYSTEM”
on page 2-15
.
Make sure the fuel valve is ON.
Clean or replace the air filter.
Clean
Clogged
Check the air filter.
Choke partially open
Compression normal
Clean or replace the fuel strainer.
Clean
Clogged
Check the fuel strainer.
Clean or replace the spark arrester.
Clean
Clogged
Check the spark arrester (if equipped).
Compression
is above
80 psi
Camshaft decompressor is not working,
valve clearance excessive, or damaged
rocker arm. Inspect the decompressor
(page P. 10-23
).
Compression
is too low
Check the fuel level.
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