Honda SH125 Manual page 354

TROUBLESHOOTING
ENGINE LACKS POWER
1. Brake Drag Inspection
Raise the wheel
off
the ground and spin it by hand.
Does the wheel spin freely?
NO
-
Brake dragging
YES
-
GO TO STEP 2.
2. Tire Pressure Inspection
Check the tire pressure.
Is the pressure correct?
NO
-
Faulty tire valve
Punctured tire
YES
-
GO TO STEP 3.
3. Clutch Inspection
Accelerate rapidly.
Does the engine speed change accordingly?
NO
-
Clutch slipping
Worn clutch shoes or outer
0
Weak driven face spring
Additive in engine oil
Weight roller stuck
YES
-
GO TO STEP 4.
4. Engine Performance Inspection
Accelerate lightly.
Does the engine speed increase?
NO
-
0
Faulty idle air control (IAC) valve in ECM
Clogged air cleaner
Clogged muffler
Faulty fuel pump
YES
-
GO
TO STEP 5.
5. Spark Plug Inspection
Remove and inspect the spark plug.
Is the spark plug in good condition?
NO
-
Plug not serviced frequently enough
Incorrect spark plug heat range
Incorrect spark plug gap
YES
-
GO TO STEP 6.
6. Engine Oil Inspection
Check the oil level and condition.
Is the engine oil in good condition?
NO
-
Oil level too high
Oil level too low
0
Contaminated oil
YES
-
GO TO STEP 7.
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