Emission Control Systems; Source Of Emissions; Crankcase Emission Control System - Honda Metropolitan CHF50 Service Manual

GENERAL INFORMATION
EMISSION CONTROL SYSTEMS
SOURCE OF EMISSIONS
The combustion process produces carbon monoxide, oxides of nitrogen and hydrocarbons. Control of oxides of nitrogen
and hydrocarbons is very important because, under certain conditions, they react to form photochemical smog when
subjected to sunlight. Carbon monoxide does not react in the same way, but it is toxic.
Honda Motor Co., Ltd. utilizes lean carburetor settings as well as other systems, to reduce carbon monoxide and
hydrocarbons.
CRANKCASE EMISSION CONTROL SYSTEM
The engine is equipped with a closed crankcase system to prevent discharging crankcase emissions into the atmosphere.
Blow-by gas is returned to the combustion chamber through the air cleaner and carburetor.
'02 - '05 model:
CARBURETOR
AIR CLEANER
<^j 1 FRESH AIR
BLOW-BY GAS
After '05 model:
PCV CONTROL SOLENOID VALVE.
CARBURETOR
AIR CLEANER
FRESH AIR
BLOW-BY GAS
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