The scarcity of fossil fuels and high exhaust emissions have prompted the search for more environmentally friendly alternative fuels. One solution is to blend ethanol with 92-octane gasoline, such as Pertamax and Gasoline 92. This study aimed to determine the effect of blending ethanol with Pertamax and Gasoline 92 on the performance and exhaust emissions of a 155 cc motorcycle engine. The study was conducted using a dyno test to measure power, torque, and fuel consumption, as well as an emissions test to measure CO, CO₂, and O₂ levels in the exhaust gas. The ethanol blends used were E0, E5, E10, E15, and E20. The test results showed that the addition of ethanol affected engine performance and emissions. For Pertamax fuel, the PE20 blend produced the highest power and the best emission efficiency. Meanwhile, for Gasoline 92 (Mobil™), a blend of ME15 to ME20 provides optimal torque and power, as well as the lowest CO emissions. Average fuel consumption also tends to decrease with increasing ethanol content. CO emissions decrease with increasing ethanol content, while CO₂ and O₂ increase, indicating more complete combustion. Therefore, a 15–20% ethanol blend (E15–E20) is considered the most effective in improving performance while reducing exhaust emissions, making it more environmentally friendly and worthy of development as an alternative fuel.