Poor Performance; Rear Wheel Spins At Idle; Starting Difficulties - VESPA GT 125 Workshop Manual

Vespa GT 125-200
This section makes it possible to find what solutions to apply when troubleshooting.
For each failure, a list of the possible causes and pertaining operations is given.
Engine

Poor performance

Possible Cause
The carburettor is dirty; fuel pump or vacuum valve damaged Remove, wash with solvent and dry with compressed air or re-
Incorrect timing or worn timing system elements
Muffler obstructed
Air filter blocked or dirty.
Automatic starter failure
Oil level exceeds maximum
Lack of compression: parts, cylinder and valves worn
Transmission belt worn
Inefficient automatic transmission
Clutch slipping
Carburettor nozzles clogged

Rear wheel spins at idle

Possible Cause
Idling rpms too high
Clutch fault
Intake coupling cracked or clamps incorrectly tightened

Starting difficulties

Possible Cause
Altered fuel characteristics
Rpm too low at start-up or engine and start-up system dam-
Incorrect valve sealing or valve adjustment
- Engine flooded.
Automatic starter failure
Air filter blocked or dirty.
POOR PERFORMANCE
REAR WHEEL TURNING WITH IDLE ENGINE
DIFFICULT STARTING
aged
Operation
place
Time the system again or replace the worn parts
Replace
Dismantle the sponge, wash with water and shampoo, then
soak it in a mixture of 50% petrol and 50% of specific oil (Se-
lenia Air Filter Oil), then hand dry without squeezing, allow to
drip dry and then reassemble.
Check: mechanical movement, electric connection and fuel
supply, replace if required.
Check for causes and fill to reach the correct level
Replace the worn parts
Replace
Check the rollers and the pulley movement, replace the dam-
aged parts and lubricate the driven pulley moveable guide with
Montblanc Molybdenum Grease
Check the clutch system and/or the bell and replace if neces-
sary
Dismantle, wash with solvent and dry with compressed air
Operation
Adjust the engine idle speed and the CO%, if necessary.
Check the springs / clutch masses
Replace the intake coupling and check the clamps are tight-
ened
Operation
Drain off the fuel no longer up to standard; then, refill
Check the starter motor, the system and the torque limiter
Inspect the head and/or restore the correct clearance
Try starting-up with the throttle fully open. If the engine fails to
start, remove the spark plug, dry it and before refitting, make
the motor turn so as to expel the fuel excess taking care to
connect the cap to the spark plug, and this in turn to the ground.
If the fuel tank is empty, refuel and start up.
Check: mechanical movement, electric connection and fuel
supply, replace if required.
Dismantle the sponge, wash with water and shampoo, then
soak it in a mixture of 50% petrol and 50% of specific oil (Se-
Troubleshooting
TROUBL - 61