Suzuki Madura GV700GL Service Manual page 198

7-3 EMISSION CONTROL & REGULATIONS
GENERAL EMISSION INFORMATION
There are three different types of regulated exhaust emissions. They are:
Hydrocarbons (HC)
Carbon Monoxide (CO)
Oxides of Nitrogen (NOx)
Automobiles must meet specific emission standards for all three of these pollutants. Motorcycles must
only meet the requirements for the following:
Hydrocarbons (HC)
Carbon Monoxide (CO)
HC exhaust emissions are basically unburned fuel vapors which have passed through the engine and escaped
the combustion process.
CO exhaust emissions are formed during an incomplete combustion cycle as a result of a rich air/fuel mix-
ture. The only way that CO can be produced is by the combustion cycle.
Total NOx emissions from all motorcycles is considered negligible. The EPA states that total NOx emission
from motorcycles by 1990 will only amount to approximately 0.5%. NOx is formed during the combus-
tion process at high combustion chamber temperatures.
CARBON MONOXIDE
Carbon monoxide is a product of an incomplete combustion cycle. CO is measured in grams per mile or
kilometer and also in percentage (%).
The most common cause of CO is rich carburetion. As the mixture is richened excessively, the CO amount
increases proportionately. Engine oil is also a hydrocarbon, so engine problems which lead to oil burning
increase carbon monoxide.
CARBURETION MALFUNCTION
1. Air Cleaner- Dirty or over oiled.
2. Idle Mixture- Adjusted incorrectly.
3. Idle Speed- Too high or low.
4. Fuel Level -Sticking float, leaking needle, incorrect setting
5. Choke- Leaking or linkage sticking.
6. Synchronization- Improper balance on multi cylinders.
ENGINE MALFUNCTION
1. Valve Seals- Leaking or torn.
2. Valve Guide- Worn and leaking excess oil.
3. Gaskets- Leaking oil into combustion chamber.