Exhaust Emission Control System - Honda NSS250S Manual

GENERAL INFORMATION

EXHAUST EMISSION CONTROL SYSTEM

The exhaust emission control system is composed of a pulse secondary air supply system, a three-way catalytic converter
and PGM-FI system.
SECONDARY AIR SUPPLY SYSTEM
The pulse secondary air supply system introduces filtered air into the exhaust gases in the exhaust port. Fresh air is drawn
into the exhaust port by the function of the PAIR control solenoid valve.
This charge of fresh air promotes burning of the unburned exhaust gases and changes a considerable amount of
hydrocarbons and carbon monoxide into relatively harmless carbon dioxide and water vapor.
The reed valve prevents reverse air flow through the system. The PAIR control solenoid valve is operated by the solenoid
valve. The solenoid valve is controlled by the PGM-FI unit, and the fresh air passage is opened/closed according the
running conditions (ECT, TP sensors and engine revolution).
No adjustments to the secondary air supply system should be made, although periodic inspection of the components is
recommended.
AIR CLEANER HOUSING
PAIR CONTROL
SOLENOID VALVE
FRESH AIR
EXHAUST GAS
THREE-WAY CATALYTIC CONVERTER
This scooter is equipped with a three-way catalytic converter.
The three-way catalytic converter is in the exhaust system. Through chemical reactions, they convert HC, CO and NO
the engine's exhaust to carbon dioxide (CO
No adjustment to these systems should be made although periodic inspection of the components is recommended.
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), nitrogen (N ) and water vapor.
2 2
THROTTLE BODY
EXHAUST PORT
REED VALVE
X
in