Honda TRX450ER Owner's Manual page 130

Engine Idle Speed
and Air-Fuel Mixture
Air-Fuel Mixture Adjustment
Pilot screw is available to compensate for air-fuel mixture. For those
who are mechanically proficient and have the necessary tools,
adjustment procedures are given in the official Honda Shop Manual
available from your Honda dealer. All others should have this carburetor
modification performed by a Honda dealer.
Servicing Your Honda 121