VESPA GTV 125, Service Station Manual

Page: 160 / 278

Inspecting the by-pass valve
- Check the unloaded spring length.
- Check that the small piston is not scored.
- Ensure that it slides freely on the crankcase and that it guarantees a good seal.
- If not, eliminate any impurities or replace defective parts.
Characteristic
By-pass check up: Standard length
54.2 mm
Refitting the oil sump
- Refit the by-pass valve plunger in its housing.
- Insert the pressure-regulating spring.
- Fit a new sump seal.
- Refit the two centring dowels.
- Refit the sump, taking care to locate the spring in
the appropriate recess machined into the inside of
the sump.
- Refit the rear brake cable brackets and the
screws in the reverse order from which they were
removed.
- Tighten the screws to the prescribed torque.
- Refit the driving pulley assembly, the drive belt,
the sprocket wheel and the transmission cover, as
described in the "Transmissions" chapter.
- When testing the lubrication system, refer to
chapter "Crankcase and Crankshaft", regard-
Engine
Vespa GTV 125
ENG - 62