The compressed natural gas (CNG) is an eco-friendly fuel was used in this paper for the gasoline engine convert to CNG engine. The modification was giving more advantage in emission. Here focus is to improve the average of the vehicle. CNG is considered to be more environmental friendly. There are considerably less pollutants associated with compressed natural gas being ignited, and studies show that it gives off 40% less greenhouse gas. CNG is a nontoxic fuel that does not pose any danger of contamination. In this paper we use a second fuel tank (CNG cylinder) and 2-wheeler (Hero Honda cd 100), which has to be attached at the back of motorcycle. This paper represents installing CNG kit, component of CNG kit, cost and maintenance, working and testing, functioning, performance and also deals with safety concern.