It is well know that better fuel economy, good drivability, lower cost are essential for motorcycle market in Asia. To meet these demands in the meantime is a challenge for engineers. Gas motion in cylinder has significant effects on engine combustion efficiency and stability. A simple gas motion control valve may be a solution to meet these demands. This paper examines the turbulence characteristics combustion and fuel consumption between swirl valve and tumble valve on an air cooled 150cc four valves scooter engine. Finally, the swirl valve and tumble valve respectively improve the fuel consumption about 12% and 17% in the partial load 4500rpm, 2bar BMEP engine operating condition.