Honda NRX1800 2004 Owner's Manual page 212

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.
Emission Control Systems
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 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 solenoid valve is open,
fuel vapor in the charcoal canister and air
cleaner is drawn into the engine through
the throttle body.
Technical Information
203