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On April 2020, India will move from Bharat Stage IV to Bharat Stage VI where the combined emission limit of Total Hydrocarbons (THC) and Nitrogen oxides (NOx) of 0.79g/km will independently reduce to 0.1g/km and 0.06g/km respectively. This reduction in emission limit however may prove to be challenging for small engines (below 200 cc) with the existing generation of engines predominantly in cold operating conditions. When the vehicle is started after soaking (engine turned off for few hours), considerable amount of THC emission is generated which can be attributed to poor fuel vaporization and incomplete combustion due to flame quenching in the combustion chamber. Also, the catalyst is inactive to chemical reactions until the accumulated heat energy from the hot exhaust mass flow elevates the catalyst temperature to facilitate efficient conversion of THC, CO and NOx to H2O, CO2 and N2. This temperature point is termed as catalyst light off temperature.

Today, nations are in the path of low-emission transformation mandating stricter emission norms with periodic revisions. With the expected introduction of Bharath Stage VI (BS VI) for two wheelers in India by 2020, limitation in primary pollutants namely - Carbon Monoxide (CO), Total Hydro-Carbons (THC) and Nitrogen Oxides (NOx) are reduced by 50%, 75% and 85% respectively in comparison to the existing Bharath Stage IV. The original equipment manufacturers (OEMs) are identifying measures to improve the overall efficiency and raw emissions from the engine through strategies like multi-spark configurations, improved charge induction concepts, liquid cooling, lean combustion etc. With end user demands for performance, low end torque, high power to displacement ratio, quick acceleration and fuel efficiency, the balance with the emission regulation is expected to be challenging.