Ducati Monster S4R Owner's Manual page 150

Noise and exhaust emission control system
information
Source of Emissions
The combustion process produces carbon monoxide and
hydrocarbons. Control of 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 is toxic.
Ducati utilizes lean carburetor settings and other systems
to reduce carbon monoxide and hydrocarbons.
Exhaust Emission Control System
The Exhaust Emission Control System is composed of
lean carburetor settings, and no adjustments should be
made except idle speed adjustments with the throttle
stop screw. The Exhaust Emission Control System is
separate from the crankcase emission control system.
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 the throttle body.
Evaporative Emission Control System
California motorcycles are equipped with an evaporative
emission control system which consists of a charcoal
canister and associated piping. This system prevents the
escape of fuel vapors from the throttle body and fuel tank.
E
75