VESPA 664787, Service Station Manual

Page: 96 / 179

- Disconnect the fuel supply and the suction taking
pipe from the carburettor.
- Check that there are no fuel leaks between the
two tubes.
- Close the fuel outlet pipe.
- By means of the MITIVAC pump apply 0.1 bar of
suction to the tap.
- Make sure that the suction is kept stable and that
and that there are no fuel leaks.
- Reconnect the suction pipe to the manifold.
- Position the fuel pipe with the outlet at the point
of the tap.
- Turn the engine by using the starter for five sec-
onds with the carburettor at minimum.
- Take up the fuel by means of a graded burette.
N.B.
THE MEASUREMENT MAY BE FALSIFIED BY THE INCOR-
RECT NUMBER OF REVS OR BY THE WRONG POSITION
OF THE TUBE.. IN THIS CASE, THE TENDENCY IS TO OB-
TAIN A REDUCED FUEL FLOW RATE. THE SUCTION OUT-
LET ON THE MANIFOLD HAS A SECTION INTENTIONALLY
REDUCED FOR THE PURPOSE OF ENHANCING THE SUC-
TION PULSATION AND THEREBY GUARANTEE A CON-
STANT TAP FLOW RATE.
Specific tooling
020329Y MityVac vacuum-operated pump
Characteristic
Minimum flow rate
20 cc
Engine
Vespa S 50 2T
ENG - 96