Gilera 633721 Workshop Manual page 279

Nexus 500 euro 3
To prevent wear of the adjustment piston, opera-
tion at full speed is obtained with a minimum open-
ing of 43 - 45 "steps".
To recover possible adjustments, every switching
to "OFF" causes the piston to close up to end of
travel and to open up again by a fixed number of
steps (self-reset).
When the control unit changes the Stepper open-
ing "steps" it also changes the injection time to
ensure proper ignition.
The engine idle speed is practically stabilised at
1550-50 rpm. After a hot start-up step you can
perceive the first increase in the revolutions and
the subsequent closing of the Stepper to stabilise
the speed.
In case of irregular speed, before carrying out
electric checks inspect the throttle valve and the
auxiliary air circuit cleaning.
To check the Stepper and the relevant circuit, pro-
ceed as follows:
1 - Connect the diagnostic tester.
Set the switch to "ON" with switch to "RUN" and
side stand raised.
Lift the scooter on the central stand. Select the
function "ERRORS" in the menu.
Check whether the control unit has detected any
failures relating to the Stepper circuit.
YES go to 8 NO go to 2
Specific tooling
020460Y Scooter diagnosis and tester
2 - Select the menu on the "PARAMETERS" function. Check the number of "steps" programmed by
the control unit to obtain start-up. This setting is a function of the engine temperature.
Electric characteristic
20° C =
approx. 135 - 140 steps
Injection
INJEC - 279