The two motorcycles were tested on a two-wheeler chassis dynamometer (AVL Zollner 2000—single roller) which simulated vehicle inertia and road load resistance (Fig.1). This bench is designed to simulate the road load (including vehicle inertia) and to measure the exhaust emissions during dynamic speed cycles. Using this system, it is also possible to carry out tests in constant speed mode, constant tractive force mode and constant acceleration mode. The chassis dynamometer was set by using the running resistance table according to the procedures laid down in Directive 2003/77/EC. Before each test in cold start conditions, the motorcycles were kept at a relatively constant temperature between 20 and 25 C for at least 8 h.