Derbi boulevard 125 4t Workshop Manual page 151

Engine
Inspecting the valve and needle
- Check that the tapered pin of the vacuum valve
does not show wear.
- Check that the depression valve does not show
threads on the external surfaces.
- Check that the vacuum intake hole is not clogged.
- Check that the diaphragm is not damaged or has
hardened, otherwise replacement the whole valve.
- Insert the tapered pin into the vacuum valve
housing.
- Reassemble the vacuum valve on the carburettor
body taking care that the tapered pin is inserted
into the sprayer.
N.B.
THE VALVE CAN BE INSERTED IN ONLY ONE
POSSIBLE POSITION.
- Reassemble the spring with the pin lock.
- Remove the cover of the vacuum chamber being
careful to correctly insert the spring in its place on
the cover.
- Tighten the screws.
ENG - 151