Seeing the impact of the fossil energy crisis is increasingly scarce government tackle by utilizing biomass energy. The use of gasification will generally save fuel costs. The purpose of this study was to determine the effect of exhaust diameter variation on combustion temperature, initial ignition time and effective flame time on the rice husk gasification type downdraft continue. The study was conducted by varying the diameter of the exhaust, with a 10 mm diameter exhaust, 20 mm exhaust diameter and 30 mm diameter exhaust. then taken the data include combustion temperature, initial startup time and effective flame time. The results showed that the exhaust diameter variation influenced the combustion temperature, the initial ignition time and the effective ignition time produced. The highest average temperature of 30 mm diameter exhaust is 534,268°C, the fastest ignition time is 10 mm diameter exhaust at minute 5 and the longest effective flame is in the exhaust diameter of 10 mm to 53 minutes
