VESPA 946 E4 EMEA 2021 Manual page 190

Engine
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 defec-
tive parts.
Characteristic
Standard length
52.4 mm
Piston standard diameter
12.861 + 12.843 mm
Refitting the oil sump
- Refit the by-pass piston in its housing.
- Insert the pressure-regulating spring.
- Fit a new sump seal.
- Refit the sump, taking care to locate the spring in
the appropriate recess machined into the inside of
the sump.
- Refit the rear brake transmission mounting brack-
ets 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 "Transmission" chapter.
- When testing the lubrication system, refer to
the "Crankcase and Crankshaft" chapter, re-
garding lubrication of the connecting rod as-
sembly
Locking torques (N*m)
Tightening torque
11 to 13
ENG - 190
Vespa 946 E4-E5 EMEA-USA-ASIA (2021-)