The lean combustion of an SI engine has been recognized as one of the most promising method of further improvement of fuel economy. According to automotive pollution point of view, exhaust emissions as NOx, CO &HC are reduced because of abundance of oxygen and lowering of peak temperature. The present study was aimed at ascertaining the benefits of employing catalysts in the combustion chamber of an SI engine. In our study we have tried to combine the concept of catalytic coating and lean burn to improve performance of an SI engine. The literature study has revealed that there is enormous potential for catalytic coatings in the automotive engines. We have chosen 100CC YAMAHA RX100 engine in our study because these two stroke engines are one of the greatest monsters that could demolish the atmosphere. In our investigation we have used a silver catalyst and nickel catalyst in 100CC engine. Experiments were conducted using multi utility roller test bench and exhaust analyzer. As the result of coating of catalysts such as nickel and silver the mileage of the vehicle has been increased by nearly 10%.