The Experimental Study On Transient Emissions And Engine Behaviors Of A Sporting Motorcycle Under World Motorcycle Test Cycle

In this study, the THC, CO/CO2 and NOx emissions were investigated by experimental measurements on a twin-spark sporting motorcycle under real-world driving. The emissions at two typical engine steady-state operating points were also added for comparison. Meanwhile, the engine working status was monitored during the whole trip. The results indicate that the small throttle opening and the rich air/fuel ratio make the very low engine combustion efficiency during cold-start phase, which leads to higher THC and CO emissions. During this stage, the CO2 is also high due to the absolutely high fuel consumption rather than the high combustion efficiency, due to the low NOx emission. By comparing this studied engine to others, the direction to improve the transient response especially under low loads was found. Compared with steady-state operation, both CO and CO2 during transient driving are lower, because at transient driving the combustion temperature is lower, leading to lower products amounts for those CO precursor (especially for HCO). The lower combustion temperature also leads to lower NOx emission, and the incomplete combustion leads to higher THC emission at cycle driving. In a word, the lower volume efficiency and delay ignition timing result in poorer combustion status during transient driving. (C) 2020 Elsevier Ltd. All rights reserved.