2005-2008 Honda ATV TRX500FA/FGA Fourtrax, Rubicon Factory Service Manual, Page 49Get this manual
GENERAL INFORMATION SERVICING THE HONDA U.S.AOnly Maintenance, replacement or repair of the emission control devices and systems may be performed by any ATV repair establishment or individual using parts that are "certified" to EPA standards
PROHIBITED ACTIONS
The following prohibitions apply to everyone with respect to the engine's emission control systemYou may not remove or disable any device or element of design that may affect an engine's emission levelsThis restriction applies before and after the engine in placed in service