The objective of this research was to observe that amount of CO gas produced by vehicles in the present of kerosene in their fuel (premium). Concentration of CO gas emitted was determined by NDIR CO gas analyser. Gas was collected from four trademark motor cycle: Honda, Yamaha, Suzuki and Vespa. Sampling was done on authorised service center, and the gas was collected after all motor cycle samples had just been serviced. Concentration of kerosene in the premium was varied from 0% to 20% (v/v). The gas emitted from “knalpot” was collected in 10 litres plastic ball and only 1 ml of gas is needed for analysis. The smallest CO gas emission was observed in Suzuki, followed by Yamaha, Honda and Vespa.