Emission Performance of Motorcycles: Regulated and Non-Regulated Pollutants under Harmonized and Extended Testing Conditions

This study investigates emissions from motorcycles, focusing on both regulated gaseous pollutants (e.g., CO, NOx, HC) and particulate number (PN) emissions, which are non-regulated for this vehicle category in the actual EU emission regulation. Using a state-of-the-art testbench setup equipped with advanced exhaust gas analysis and PMP system, emissions were analyzed under both standardized homologation cycles and more dynamic Real Driving Cycles (RDCs). Besides the measurement results the technological differences between different motorcycle categories are described. This is followed by a discussion of the influences of engine and exhaust gas aftertreatment systems on emission. The findings reveal that, there are two different subcategories of two-wheeler, which show different emission characteristics. L1e vehicles showed increased emissions compared to passenger cars, caused by the absence of advanced exhaust aftertreatment and on-board diagnosis systems which is driven by less stringent regulations and technical constraints. L3e vehicles in contrast own comparable exhaust aftertreatment systems to passenger cars, but are operated in higher dynamics and therefore show emissions up to three times higher under real-world conditions compared to standardized test cycles, driven by high-load phases, acceleration enrichment, and distinct operating characteristics. The results underscore significant values of PN emissions in motorcycles compared to passenger cars. Stricter regulations, including PN limits, are essential, along with the development of more realistic testing methods and cycles tailored to motorcycles' unique operational characteristics to lower real world particulate emission. These measures are vital to mitigate the environmental impact of motorcycles and achieving equitable emissions reductions.