Subsequently, these norms were progressively tightened. BS III emission norms are about 7% for CO and 10% for HC + NOx of the norms introduced in 1991. Emission norms from BS I (2000) to the proposed BS IV norms for 3 wheelers has seen a reduction of 75% for CO and 47% for HC + NOx for SI engines. The order of reduction is similar to what transpired in Europe’s Tricycles over 17 years where the permissible limits were reduced by 85%.
Over and above tightening the CO, HC + NOx limits, a deterioration factor of 1.2 was introduced in the year 1998. From the year 2000 onwards, a relaxation of 20% given for conformity of production (CoP) was removed by the Government, which led to maintenance of very strict production control with minimum variations.
As per Government Notification GSR 84 (E) 2009 and GSR 443 (E) 2010, the Emission Standard for 2 wheeler and 3 wheeler applicable in all the States and the Union Territories except National Capital Region and the cities of Mumbai, Kolkata, Chennai, Bangalore, Hyderabad including Secunderabad, Ahmedabad, Pune, Surat, Kanpur, Agra, Sholapur, and Lucknow in respect of 2 wheelers and 3 wheelers manufactured on or after 1st October 2010.
For gasoline two-wheelers, other than mopeds, WMTC is applicable for setting the BS III, BS IV and BS V Two Wheeler emission norms. The Government had notified Worldwide Harmonized Motorcycle Emissions Certification (WMTC) vide G.S.R. 515(E), 29th June, 2012. Please note that WMTC is optional. Some of manufacturers depending upon their facilities are following this cycle.
Alternate Mass Emission Standards (Bharat Stage III) for two wheeler gasoline vehicles, with engine capacity exceeding 50cc or a maximum design speed exceeding 50 km/hour, based on WMTCprocedure shall be as under:-
The Government of India released the latest notification GSR 431 (E) 4th July 2014 regarding Mass Emission Standards (BSIV) which shall come into force for Two wheelers manufactured on and after the 1st April, 2016 for new types of vehicle models and from the 1st April, 2017 for existing types of vehicle models-
Mass emission standards (Bharat Stage IV) for two wheelers, with engine capacity exceeding 50 cc and a maximum design speed exceeding 50 km per hour, based on World-wide Harmonized Motorcycle Test Cycle (WMTC)
The mass emission standards shall be same as those applicable for diesel three-wheelers.
As per Report of AFV&P 2025, May 2014, BS V Emission norms are proposed with a further emission reduction over BS IV norms. The values are given below for Gasoline two wheelers of Classes 1, 2 & 3. The details are given below. BS V emission norms for two wheelers in India will be applicable four years after the implementation of BS IV emission norms for two wheelers.
Note: Applicable for new models from 1 April 2020 and existing models from 1 April 2021.
The CO limits are significantly tighter than BS IV limits; that for HC and NOx are combined with a separate sub-limit for NOx. Indian two wheelers are one Emission Norms for Three Wheeler for BS IV and BS V Regimes of the best in the world on fuel economy. This superior fuel economy has been achieved mainly by designing the engines with lean mixture (air fuel ratio is considerably above stoichiometric ratio). Use of lean mixture ratio, while improving the fuel efficiency and CO emissions tend to increase NOx emission. Therefore, in order to control the likely NOx emissions from two wheelers, an additional limit for NOx is being proposed within the overall limit of HC + NOx. However, this may limit the extent of fuel efficiency that can be achieved from two wheelers in future.
BS V Emission Norms Two Wheelers with cc < 50 and Vmax < 50 km/h and Diesel Two Wheelers
As per Report of AFV&P 2025, May 2014, Since these classes of two wheelers are not being produced in India, it is recommended that these norms may be developed by the concerned Ministry, as and when their production in India becomes significant or when such norms are included in GTR based on the Environmental and Propulsion Performance Requirements (EPPR).
As per Report of AFV&P 2025, May 2014, BS III emission norms for 3-wheelers were notified vide GSR 84(E)/9 February 2009 and implemented from 1 April 2010 in some parts of country and from 1 October 2010, all over India. It is proposed that the BS IV emission norms for 3-wheelers be as given in the table below. They will become effective from 1 April 2016.
Three Wheeler Emission Norms for SI and CI Engines – BS IV
Note:
As per Report of AFV&P 2025, May 2014, With the implementation of BS IV emission norms, Indian 3-wheelers, which are predominantly carbureted, will be tuned for lean operation which will keep the fuel efficiency as high as possible. Any further reduction in the NOx limits would not be possible with carbureted technology. A shift will have to be made towards adoption of stoichiometric ratio and the use of a 3-way catalytic converter will be needed in the case of SI engine.
For CI engines, further reduction in emissions beyond proposed BS IV emission norms will require the incorporation of technologies such as Turbo Charger, High pressure injectors, Sensors and ECU to improve engine efficiency which have not been developed. The proposal for BS V emission norms for 3-wheelers is given at table below: