2006-2009 Honda TRX250EX/TRX250X Service Manual, Page 38Get this manual
GENERAL INFORMATION
EMISSION CONTROL SYSTEMS
The U,SEnvironmental Protection Agency (EPA)and California Air Resources Board (CARB) require that offroad 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 becauseunder 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 systems to reduce carbon monoxide, oxides of nitrogen, and hydrocarbons