Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, methanol is known as one of the most suited renewable, bio-based and eco-friendly fuel for sparkignition (SI) engines. The purpose of this study is to experimentally analysis the performance and the pollutant emissions of a four-stroke SI engine operating on methanol-unleaded gasoline blends MO, M10, M20, M30 and M40 containing 0%, 10%, 20%, 30% and 40% of methanol by volume respectively. The performance tests were carried out at a wide open throttle and variable speed conditions, over the range of 1750 to 3250 rpm. The lost of heat energy with exhaust was measured with exhaust calorimeter. The experimental results revealed that even though torque, power, exhaust temperature and lost of heat energy with exhaust were decreased, specific fuel consumption (SFC) and volumetric efficiency were increased. The concentration of carbon monoxide (CO) and hydrocarbon (HC) emissions were decreased when methanol blends were introduced. This was due to the high oxygen percentage in the methanol.