Improving Purifying Exhaust Gas by a Muffler Device with Catalysts in the Motorcycle Exhaust Pipe

A muffler device with catalysts for improving purifying exhaust gas of nitrogen oxides within a motorcycle exhaust pipe comprises a muffler divided into three chambers, a firstchamber, a second chamber, and a third chamber; a front exhaust pipe; a front reduction catalyst; a rear exhaust pipeprovided with a secondary air inlet behind thereduction catalyst for introducing secondary air therein. Thereby, the exhaust gas from an engine with air-to-fuel ratio less than or equalto 14.7 will firstly pass the reduction catalyst to have its nitrogen oxides (NOX) effectively inverted into nitrogen (N2) and oxygen (O2),and then secondary air will be added to theexhaust gas so as to increase its air-to-fuelratio to larger than 14.7, and finally the exhaust gas will pass the oxidation catalyst to have its carbon monoxide (CO) and hydrocarbons (HC) effectively inverted into carbon dioxide (CO2) and water (H2O