Honda 2006 CB600F Owner's Manual page 231

Emission Control Systems
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.
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Technical Information
Evaporative Emission Control System
(California only)
This motorcycle 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 absorbed 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.