Catalytic Silencers - APRILIA 6.5 - 1996 Manual

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Avoid parking the catalytic ve-
hicle near dry brush wood or in
places easily accessible to child-
ren, as the catalytic silencer becomes
extremely hot during use; be very
careful and avoid any kind of contact
before it has completely cooled down.
The catalytic vehicle is fitted with two si-
lencers with metal catalytic converter of
the "platinum-rhodium bivalent" type.
This device provides for the oxidation of
the CO (carbon monoxide) and of the HC
(unburned hydrocarbons) contained in
the exhaust gases, changing them into
carbon dioxide and steam, respectively.
Due to the catalytic reaction, the high
temperature reached by the exhaust
gases makes for the burning of the oil
particles, thus keeping the silencer clean
and eliminating the exhaust fumes.
To have the catalytic converter function
correctly and for long and to reduce
possible problems regarding the soiling
of the thermal unit and of the exhaust, it
is necessary to avoid covering long dis-
tances with the engine running at con-
stantly low rpm.
It is sufficient to alternate these periods
with periods in which the engine runs at
relatively high rpm, even if only for a few
seconds, but rather frequently.
What has been stated above assumes
particular importance for the cold starting
of the engine: in this case, in order to
reach a rpm regime sufficient to enable
the "priming" of the catalytic reaction, you
just need to make sure that the tempera-
ture of the thermal unit has reached at
least 50° C, which generally occurs a few
seconds after starting the engine.
Leaded petrol destroys catalytic
silencers! Do not use leaded pe-
trol for the catalytic version of
the vehicle.
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