The working principle of the SAS for Quasar 250
cc Euro 2 engines is entirely similar to the SAS
employed on 2-stroke engines. The main differen-
ces are the following:
Secondary air enters directly into the exhaust duct
on the cylinder head, instead of entering through
the exhaust pipe as in two-stroke engines.
The reed valve found on 2-stroke engines is here
replaced by a membrane.
Unit «A», shown in the figure, is provided with a
cut-off connected to the vacuum inlet on the intake
manifold to shut air inlet during deceleration, so to
prevent detonations in the silencer. Air is sucked
in through hole «B» and flows inside the duct into
air-box «C» where it is filtered by filtering element
«D».
The filtered air now enters membrane device «A»,
through duct «E» and is then guided towards the
head.
Flowing through pipe «F», flanged to the head,
secondary air reaches the exhaust duct thus pro-
viding oxygen addition to the unburnt gases just
before they enter the catalytic converter.
The efficiency of the catalyzing process is there-
fore increased.
Characteristics B 125-250
CHAR - 12
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