Exhaust emission analysis of a motorcycle equipped with a Dual-Fuel Pertalite–LPG System under varying LPG flow rates and engine speeds

The increasing dependency on fossil-based fuels and the rise in vehicular exhaust emissions have intensified the search for environmentally friendly alternative fuels. This study aims to investigate the effect of varying liquefied petroleum gas (LPG) flow rates on the exhaust emissions of a motorcycle operating on a dual-fuel system combining Pertalite and LPG. Experimental tests were conducted on a four-stroke motorcycle with a manual transmission and a carburetor-based fuel system, under a range of engine speeds (1400–2000 rpm) and three LPG flow rates: 0.2, 0.5, and 0.8 L/min. The measured emission parameters include carbon monoxide (CO), hydrocarbons (HC), and carbon dioxide (CO2). The results demonstrate that an LPG flow rate of 0.5 L/min yields the highest CO2 emissions and relatively lower CO and HC levels compared to 0.2 and 0.8 L/min. In contrast, the 0.8 L/min flow rate exhibits signs of incomplete combustion, as indicated by elevated CO and HC emissions and a decline in CO2 concentration. The findings highlight the need for an optimal LPG flow rate to achieve efficient combustion and minimal emissions. The dual-fuel Pertalite–LPG system presents practical potential, particularly when integrated with a more advanced air–fuel ratio control system.