A prechamber assembly for a cylinder of a combustion engine is disclosed in which a plurality of ports placing a prechamber volume in fluid communication with the cylinder. A non-actuated, fixed orifice extends between the prechamber volume and a passageway formed in the prechamber assembly to permit combustion gases in the prechamber volume to enter the passageway. The passageway is configured to vent combustion gases therein out of the body. The orifice may reduce NOx emissions produced in the prechamber volume.