2003 Honda ATV TRX650FA Rincon Factory Service Manual, Page 39Get this manual
GENERAL INFORMATION
EMISSION CONTROL SYSTEMS
The California Air Resources Board (CARB) requires manufacturers to certify that their ATVs comply with applicable exhaust emissions standards during their useful life, when operated and maintained according to the instructions provided
SOURCE OF EMISSIONS
The combustion process produces carbon monoxide, oxides of nitrogen and hydrocarbonsControl of hydrocarbons and oxides of nitrogen 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 lean carburetor settings as well as other systems, to reduce carbon monoxide and hydrocarbons
EXHAUST EMISSION CONTROL SYSTEM
The exhaust emission control system is composed of lean carburetor setting, and no adjustments should be made except idle speed adjustment with the throttle stop screwThe exhaust emission control system is separate from the crankcase emission control systems