Yamaha Motor Co Ltd said it had developed a palladium-based exhaust emission cleaning system for two-stroke 50 cc scooter engines. Yamaha, the world's second-biggest motorcycle manufacturer, will introduce the exhaust system from April, when it launches a new model scooter in Japan. Yamaha is the first company to use palladium in a motorcycle exhaust system, for which it has applied for 15 or more patents at home and abroad, a Yamaha spokesman said. The exhaust system features a palladium catalyser in addition to a conventional catalyser that uses platinum and rhodium.