With growing concern to protect the atmosphere, the stringency of vehicle emission regulations is increasing annually [1,2]. Notably, evaluations of real driving emissions (RDEs) using portable emission measurement systems (PEMS) have been mandated for light duty vehicles (LDVs) in regions, such as the EU, China, India, and Japan [3,4]. Additionally, RDEs have attracted attention in motorcycles and was investigated in the effect study of the environmental step Euro 5 [5]. However, some inherent problems remain with RDE measurements using the PEMS on motorcycles. Due to the smaller engine displacement and fewer cylinders associated with motorcycles, resulting in lower exhaust gas flow rates, the measurement accuracy of the PEMS may be lower than that of the LDVs. Furthermore, exhaust emissions can be affected by the additional weight of the PEMS when mounted on motorcycles. This study investigated the accuracy of the PEMS in measuring motorcycle emissions by simultaneously measuring exhaust gas emissions using both the PEMS and laboratory-based analyzers. In addition, the effect of additional weight due to the PEMS installations on exhaust emissions during RDE tests was evaluated.
The results show the problem in directly applying the current PEMS for LDVs, to motorcycles without modifications, in terms of PEMS measurement accuracy. The additional weight associated with the installation of the PEMS also has a significant impact on exhaust emissions. These results indicate the difficulties of using the current PEMS for LDVs to motorcycles. To accurately measure the RDE of motorcycles, improving the measurement accuracy of the PEMS and reducing their weight are crucial. Meanwhile, it is expected that methods for measuring the RDE on motorcycles that do not use PEMS (e.g., random cycle testing using C/D [6]) will also be investigated.