Honda TRX250TE 2019 Owner's Manual page 142

Engine Idle Speed and Air-Fuel
Mixture
Air-Fuel Mixture Adjustment
The pilot screw (2) 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 dealer. All others should have this carburetor
modification performed by your dealer.
132
Servicing Your Honda