VESPA GT 125 Workshop Manual page 183

Vespa GT 125-200
Engine
- Remove the drainage screw from the tank, wash
and blow the tank properly and make sure the ac-
celeration pump intake and supply valve are clean.
- Being the valves unidirectional, blow them care-
fully with compressed air, at the inner side of the
tank for the intake valve and at the pump piston
housing for the supply valve.
- Check that there are no signs of wear in the ac-
celeration pump piston and its corresponding seat
in the tank.
- In case of wear, replace the defective parts.
- Check that the acceleration pump piston contrast
spring is not worn.
- Assemble a new O-Ring and a new bellows gas-
ket. Reassemble the piston unit on the tank.
- Assemble a new O-Ring on the tank drainage
screw and lock it.
-Check the screw tightness introducing a small
amount of fuel in the tank.
- Assemble a new gasket on the tank.
- Assemble the tank on the carburettor body fas-
tening the 4 screws.
- Wash and blow the flow screw properly and as-
semble a new O-Ring.
- Preassemble the components on the screw as
follows: spring, washer and O-ring.
- Screw the flow screw on the carburettor body.
- The screw final position should be determined by
an exhaust fumes analysis.
ENG - 183