Sym GTS 250 Service Manual page 19

1. General Information
C. Engine runs sluggish (especially in low speed and idling)
Check and adjustment
Check ignition timing
(Using ignition lamp)
Normal
Adjust the air screw of
carburetor
Good
Air sucked through
carburetor gasket
No air sucked
Remove spark plug, install
spark plug into spark plug
cap and perform spark test
against engine ground
Good spark
D. Engine runs sluggish (High speed)
Check and adjustment
Check ignition timing
Normal
Check for fuel supplying
system in automatic fuel cup
Good
Check if carburetor clogged
No clogged
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To this chapter contents
Fault condition
Abnormal
Poor
Air sucked
Poor
Fault condition
Abnormal
Poor
Clogged
Probable causes
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
Probable causes
1. Malfunction of CDI
2. Malfunction of AC alternator
1. Insufficient fuel in fuel tank
2. Fuel filter clogged
3. Restricted fuel tank vent
1. Cleaning