Exhaust Emissio Control System (Pulse Secondary Air Supply System) - Honda Motorcycle Service Manual

EMISSION CONTROL SYSTEMS
EXHAUST EMISSION CONTROL SYSTEM (PULSE SECONDARY AIR SUPPLY SYSTEM)
The exhaust emission control system is composed of lean carburetor settings and no adjustment should be made except idle
speed adjustment with the throttle stop screw.
On some models the exhaust emission control system also consists of a pulse secondary air supply system which introduces
filtered air into the exhaust gases in the exhaust port. Fresh air is drawn into the exhaust port whenever there is a negative
pressure pulse in the exhaust system. 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.
A pulse secondary air injection check valve (PAIR check valve) prevents reverse air flow through the system. The pulse
secondary air injection control valve (PAIR control valve) reacts to high intake manifold vacuum and will cut off the supply
of fresh air during engine deceleration, thereby preventing afterburn in the exhaust system.
No adjustments to the secondary air supply system should be made, although periodic inspection of the components is
remommended
PULSE SECONDARY
AIR INJECTION
VACUUM TUBE CONTROL VALVE
AIR CLEANER
Date of Issue: March. 1995
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