Engine Poor Performance; Rear Wheel Spins At Idle; Starting Difficulties; Troubleshooting - VESPA ET4 50 Workshop Manual

ET4 50
Engine
Poor performance
Possible Cause
Air filter clogged or dirty
Carburettor nozzles clogged or dirty
Dirty or faulty vacuum-operated cock
Clutch slipping
Inefficient automatic transmission
Lack of compression: parts, cylinder and valves worn
Oil level exceeds maximum
Excess of encrustations in the combustion chamber
Timing failure or timing system parts worn
Muffler obstructed
Fuel filter on vacuum operated cock blocked
Wrong valve adjustment
Valve seat distorted
Worn cylinder, Worn or broken piston rings

Rear wheel spins at idle

Possible Cause
Idling rpms too high
Clutch fault
Air filter housing not sealed
Purifier-carburettor fitting damaged

Starting difficulties

Possible Cause
Defective spark plug or with incorrect electrode gap
Battery flat
- Engine flooded.
Vacuum operated cock failure
Failing automatic starter on the carburettor
POOR PERFORMANCE
Disassemble, wash sponge with water and shampoo and im-
merse in a mixture of 50% petrol and Selenia Air Filter oil. Let
it drip. Wring out without squeezing it and then refit
Dismantle, wash with solvent and dry with compressed air
Check the filter on the cock, remove the petrol and wash the
tank, if necessary. Replace the cock as a last resource.
Check the clutch system and/or the bell and replace if neces-
Check the rollers and the pulley movement, replace the dam-
aged parts and lubricate the driven pulley moveable guide with
Check for causes and fill to reach the correct level
Descale the cylinder, the piston, the head and the valves
Reset timing phase or replace any worn parts (refer to 4-stroke
Replace the piston cylinder assembly or just the piston rings
REAR WHEEL
Check the idling speed and, if necessary, adjust the C.O.
Check the spring/friction mass and the clutch bell
Correctly refit the filter housing and replace it if it is damaged

STARTING PROBLEMS

Check and if necessary replace the spark plug and the elec-
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
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
spark plug and the spark plug grounded but away from its hole.
Refit a dry spark plug and start the vehicle.
Check that fuel is adequately supplied through the pipe by ap-
Check the electrical wiring and mechanical movement, replace
Operation
sary
Montblanc Molybdenum Grease
Replace the worn parts
50 cc engine manual)
Replace
Clean the cock filter
Adjust the valve clearance properly
Replace the head assembly
Operation
Replace
Operation
trode gap
itself
plying a vacuum to the suction pipe
if necessary.

Troubleshooting

TROUBL - 35