<p>Turbulent jet ignition (TJI) is a promising technique for extending the lean-burn limit in spark ignition (SI) engines by enabling stable ignition and rapid combustion through enhanced thermal, chemical, and turbulent effects. While research engine applications are crucial for fundamental studies and the development of new engine technologies, further investigations are required to enable the effective integration of TJI, particularly passive TJI, into existing commercial SI engines. In this study, a commercial single-cylinder SI engine originally equipped with a carburetor was modified to operate with port fuel injection and subsequently integrated with different pre-chambers for passive turbulent jet ignition (PTJI) applications. The effects of PTJI on combustion, performance, and emissions of the engine were experimentally investigated at a constant speed of 3000&#xa0;rpm under wide open throttle condition. The lean-burn limit of the engine, defined by a coefficient of variation of indicated mean effective pressure below 5%, was significantly extended to an excess air ratio of 1.5 with the implemented PTJI configurations. The most favorable combination of elevated in-cylinder pressure, improved combustion stability, and enhanced thermal efficiency was achieved with a pre-chamber featuring a volume of approximately 2&#xa0;cm³, 3.6% of the main chamber clearance volume, and six equiangular distributed nozzles, each 1.25&#xa0;mm in diameter, yielding a total nozzle area-to-pre-chamber volume ratio of approximately 0.037&#xa0;cm⁻¹. A comparative analysis was conducted between the results of the conventional SI and the PTJI modes across various excess air ratios.</p>