SANYANG INDUSTRY CO. SYM, Service Manual

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1. GENERAL INFORMATION/TROUBLE DIAGNOSIS
SYM
1-14
C. Engine runs sluggish (especially in low speed and idling)
D. Engine runs sluggish (High speed)
Check ignition timing
(using ignition lamp)
Good spark Poor
No air sucked Air sucked
Good Poor
Abnormal
Air sucked through
carburetor gasket
Adjust the air screw of
carburetor
Remove spark plug, install
spark plug into spark plug
cap and perform spark test
against engine ground
Normal
Check and adjustment Fault condition Probable causes
Check for fuel supplying
system in automatic fuel cup
Check if carburetor clogged
1. Incorrect ignition timing (malfunction
of CDI or AC alternator)
1. Rich mixture (loosen the screw)
2. Lean mixture (tighten the screw)
1. Poor heat insulation gasket
2. Carburetor lock loose
3. Poor intake gasket
4. Poor carburetor O-ring
5. Vacuum hose crack
1. Spark plug fouled
2. Malfunction of CDI
3. Malfunction of AC generator
4. Malfunction of ignition coil
5. Open or short circuit in spark plug
leads
6. Malfunction of main switch
1. Insufficient fuel in fuel tank
2. Fuel filter clogged
3. Restricted fuel tank vent
Good
Poor
Check and adjustment Fault condition Probable causes
Check ignition timing
1. Malfunction of CDI
2. Malfunction of AC alternator
Normal Abnormal
No clogged Clogged
1. Cleaning