This research aims to investigate the effect of ethanol blends with pure gasoline to the rate of fuel consumption and emissions of fuel injection motorcycle 115 cc with automatic transmission which is the population is dominant in Indonesia. Variations of the bioethanol mixture are 0%, 5%, 10%, and 20% ethanol. The experiment conducted in two different conditions by using three ways catalytic converter (TWC) in the exhaust pipe and without using TWC in the exhaust pipe. First, all engine setting was originally manufacture setting. Second, the AFR is set in stoichiometry condition (λ = 1) and ignition timing set in MBT timing using modified ECU. The experiment performed on the chassis dynamometer and referred on the standard cycle ECE 15. The results of this experiment showed that increment of ethanol content in the fuel makes the rate of fuel consumption and CO2 emission both increased but CO and HC emissions decreased. The use of modified ECU makes the rate of fuel consumption is higher because of richer AFR, but the emissions of HC and CO emission were lower compared to unmodified ECU. The lowest NOx emission in modified ECU resulted from E10 fuel while in original ECU resulted from E5 fuel. The TWC was worked optimally at modified ECU. Furthermore, E20 fuel using TWC with stoichiometric air-fuel ratio and MBT timing condition can be recommended in future research, based on fuel consumption and exhaust gas emission produced.