Tumble flow is very effective for turbulence enhancement near the spark timing, and eventually improves the combustion performances in spark-ignition engines. In this paper the effects of tumble flow on combustion characteristics in a four-valve engine was investigated by using LDV measurements and combustion pressure inside engine cylinder. Tumble flow patterns was changed by intake port flow angles which is implemented by an aluminum cassette. The results show that high tumble flow can be generated during intake by a moderate inlet angle and decreases burning duration in lean mixture operation condition.