Honda SH300 2006 Manual page 53

EXHAUST EMISSION CONTROL SYSTEM
The exhaust emission control system is composed of a secondary air supply system and PGM-FI system, and no adjust-
ments should be made. The exhaust emission control system is separate from the crankcase emission control system.
SECONDARY AIR SUPPLY SYSTEM
The secondary air supply system which 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 hydrocar-
bons and carbon monoxide into relatively harmless carbon dioxide and water vapor.
The PAIR check valve prevents reverse air flow through the system. The PAIR control solenoid valve is controlled by the
ECM, and the fresh air passage is opened and closed according to the running condition.
No adjustments to the secondary air supply system should be made, although periodic inspection of the components is
recommended.
PAIR CONTROL
SOLENOID VALVE
EXHAUST PORT
THREE-WAY CATALYTIC CONVERTER
This scooter is also equipped with the three-way catalytic converter. The three-way catalytic converter is in the exhaust
system. Through chemical reactions, they convert HC, CO and NOx in the engine's exhaust to carbon dioxide (CO
gen (N ) and water vapor.
2
NOISE EMISSION CONTROL SYSTEM
TAMPERING WITH THE NOISE EMISSION CONTROL SYSTEM IS PROHIBITED: Local law prohibits the following acts or the
causing thereof: (1) The removal or rendering inoperative by any person, other than for the purposes of maintenance,
repair or replacement, of any device or element of design incorporated into any vehicle for the purpose of noise control
prior to its sale or delivery to the ultimate customer or while it is in use; or (2) the use of any vehicle after such device or
element of design has been removed or rendered inoperative by any person.
AMONG THOSE ACTS PRESUMED TO CONSTITUTE TAMPERING ARE THE ACTS LISTED BELOW:
1. Removal of, or puncturing of the muffler, baffles, header pipes or any other component which conducts exhaust gases.
2. Removal of, or puncturing of any part of the intake system.
3. Lack of proper maintenance.
4. Replacing any moving parts of the vehicle, or parts of the exhaust or intake system, with parts other than those
specified by the manufacturer.
PAIR CHECK VALVE
GENERAL INFORMATION
AIR CLEANER HOUSING
Fresh Air
Exhaust Gas
), dinitro-
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