2006-2009 Honda TRX680 (TRX 680 FA-FGA) Factory Service Manual, Page 43Get this manual
GENERAL INFORMATION
EMISSION CONTROL SYSTEMS
The U.SEnvironmental Protection Agency (EPA), and the California Air Resources Board (CARB) require that off-road motorcycle or ATV comply with applicable exhaust emissions standards and evaporative emissions standards during its useful life, when operated and maintained according to the instruction provided
SOURCE OF EMISSIONS
The combustion process produces oxides of nitrogen (NOx), carbon monoxide (COl and hydrocarbons (He)Controlling oxides of nitrogen and hydrocarbon emissions is very important because, under certain conditions, they react to form photochemical smog when subjected to sunlightCarbon monoxide does not react in the same way, but it is toxicHonda Motor Co" Ltdutilizes various system to reduce carbon monoxide and hydrocarbons,
EXHAUST EMISSION CONTROL SYSTEM
The exhaust emission control system is composed of the PGM-FI system, No adjustments should be made The exhaust emission control system is separate from the crankcase emission control systems