VESPA 664787, Service Station Manual

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This section makes it possible to find the solutions to use in troubleshooting.
For each breakdown, a list of the possible causes and respective interventions is given.
Engine
Poor performance
P
OOR PERFORMANCE
Possible Cause Operation
Fuel nozzles or cock clogged or dirty Dismantle, wash with solvent and dry with compressed air
Excess of encrustations in the combustion chamber Remove the encrustations
Lack of compression wear of the piston rings or cylinder Check the worn parts and replace them
Exhaust pipe clogged due to excessive encrustations Replace the exhaust pipe and check the carburation and mixer
timer
Air filter blocked or dirty Clean according to the procedure
Starter inefficient (stays on) Check the mechanical sliding, continuity of the circuit, the pres-
ence of power and electrical wiring
Clutch slipping Check the centrifugal brake shoe assembly and /or clutch bell
and replace if necessary
Defective mobile pulley sliding Check all the parts, replace the faulty parts and lubricate only
the driven pulley using recommended grease
Transmission belt worn Replace
Carburettor nozzles clogged Dismantle, wash with solvent and dry with compressed air
Fuel filter on vacuum operated cock blocked Clean the cock filter
Roller wear; Presence of oil; Dirt Check the cap with filter is fitted to the transmission cover;
clean the speed variator, replace the rollers if worn out
Rear wheel spins at idle
R
EAR WHEEL
Possible Cause Operation
Idling rpm too high Adjust the idle speed
Clutch fault Check the spring/friction mass and the clutch bell
Air filter housing not sealed Correctly refit the filter housing and replace it if it is damaged
Starting difficulties
DIFFICULTY STARTING
Possible Cause Operation
Carburettor nozzles clogged or dirty Dismantle, wash with solvent and dry with compressed air
Faulty fuel cock Check that, at ignition and with throttle untwisted, no petrol
flows out the delivery pipe; otherwise, replace the vacuum-op-
erated cock
Starter inefficient Check: electric wiring, circuit continuity, mechanical sliding and
power supply
Defective spark plug or with incorrect electrode gap Check and if necessary replace the spark plug and the elec-
trode gap
Battery flat Check the state of the battery. If it shows signs of sulphation
replace it and bring the new battery into service charging it for
eight hours at a current of 1/10 of the capacity of the battery
itself
- Engine flooded. Start up keeping the throttle fully open alternating approximate-
ly five seconds of turning it with five seconds still. If however it
does not start, remove the spark plug, the engine over with the
throttle open being careful to keep the cap in contact with the
Vespa S 50 2T
Troubleshooting
TROUBL - 39