Honda NSS250A Owner's Manual page 202

Exhaust Emission Control System
The exhaust emission control system
includes a secondary air supply system,
and an oxidation catalytic converter.
No adjustment to these systems should be
made although periodic inspection of the
components is recommended.
Secondary Air Injection System
The secondary air injection system
introduces filtered air into the exhaust
gases in the exhaust port. The secondary
air injection system helps improve
emission performance.
Ignition Timing Control System
The system constantly adjusts the ignition
timing, reducing the amount of HC, CO
and NOx produced.
Emission Control Systems
Oxidation Catalytic Converter
The oxidation catalytic converter is in the
exhaust system. Through chemical
reactions, they convert HC and CO in the
engine's exhaust to carbon dioxide (CO )
and water vapor.
Evaporative Emission Control System
This scooter complies with the
requirements of the California Air
Resources Board (CARB) evaporative
emission regulations. Fuel vapor from the
fuel tank and carburetor is directed into
the charcoal canister and air cleaner where
it is adsorbed and stored while the engine
is stopped. When the engine is running
and the purge control diaphragm valve is
open, fuel vapor in the charcoal canister
and air cleaner is drawn into the engine
through the carburetor.
Technical Information
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