Ethanol fuel stands out as a notable renewable fuel to gasoline for employment in SI engines. Some severity associated with engine efficiency and emission reduction aspects involved in optimizing its blending ratios cannot be ignored. This research aims to investigate the influence of various ethanol blending ratios in conjunction with gasoline on an in-use motorcycle engine’s engine performance and emissions. Four mixing ratios of ethanol fuel consisting of 25%, 50%, 85%, and 100% were employed and compared with a reference fuel, namely gasoline. The experiments were conducted under a constant engine speed of 6500 rpm while varying loads. The results showed that while E25’s brake-specific fuel consumption closely matches that of pure gasoline (E0), it notably rises with higher ethanol content, with an increase of approximately 87% for E100 compared to E0 under varied loads. Conversely, exhaust emissions, including NOx, HC, and CO, significantly decrease with an increase in the ethanol blending ratio. Particularly notable was the observation that NOx demonstrated a pronounced upward trend with higher loads, whereas HC showed an inverse relationship.