An experimental study was conducted on a single cylinder motorcycle engine for two operating modes of full load and partial load at 6500 rpm and 8500 rpm with pure gasoline and 35% volume butanol-gasoline blend. The engine ignition timing for 35% volume butanol-gasoline blend has been optimized, and 1% volume H2O has also been added to the butanol-gasoline blend fuel. Engine performance parameters, fuel economy and emissions have been measured and analyzed. The experimental results showed that engine torque, BSEC, CO emissions and HC emissions are better than that of pure gasoline at both full load and partial load with 35% volume butanol and 1% H2O addition, combined with the modified ignition timing. But NOx and CO2 emissions are worse than that of the original level of pure gasoline. (C) 2013 Elsevier Ltd. All rights reserved.