BS 6 Special: Part 4 | BS 6 and two-wheelers

The fourth part of this special series on BS 6 emissions norms has the answers to frequent questions on BS 6-compliant motorcycles and scooters.

By Rishaad Mody, Autocar India calendar 31 Mar 2020 Views icon7692 Views Share - Share to Facebook Share to Twitter Share to LinkedIn Share to Whatsapp

Over the course of this special series on BS 6, we have  covered the evolution of the emission norms, delved into the technical aspect of upgrading engines to meet Bharat Stage 6 regulations and looked at engines that will be discontinued with the arrival of the new emission norms on April 1, 2020. Now, in this last and final part, we shift our focus to two-wheelers, the most affordable form of motorised mobility in India.

The transition to BS 6 for two-wheelers has been particularly daunting, due to the challenges of working with small engines that have been built to be as frugal as possible, both in terms of cost and efficiency. While the switch from BS 3 to BS 4 in mid-2017 was managed with relatively far fewer mechanical changes, the BS 6 emission standards are so stringent that the changes have been far more extensive, and hence, expensive.

Why are BS6 two-wheelers getting so expensive?
BS 6 emission norms are so tight that extremely precise fuelling is vital. This is why you see most mainstream manufacturers ditching the affordable and simple carburettors in their products, for more accurate, but expensive fuel-injection systems.

Considering the entire costs of the injectors, fuel pump and ECU, we are looking at a 10 percent hike in price for affordable machines, if not more. There’s also the fact that BS 6 compliance demands considerably more catalyst material, which is another significant contributor to the cost. In fact, this is one of the big reasons why you’ll see a fairly significant price hike in two-wheelers that already have FI systems.

Why no carburettors?
There are still a couple of manufacturers who have not yet fully committed to FI, but most of the big players, including Hero MotoCorp and the big Japanese manufacturers, have switched their entire line-ups to FI systems. The alternative to fuel injection is the electronically controlled carburettor, or the e-carb, which is something TVS Motor Co and Bajaj Auto are working on for their low cost, 125cc-and-below products. E-carbs are not as consistent or precise as fuel-injection systems, but they do come at a lower price, and it will be interesting to see the effects of their application.

Why are power figures dropping?
With the transition to BS 6, power and torque figures seem to dropping slightly, across the board. This is because manufacturers now essentially face a choice between cost and performance.

To put it in very basic terms, more performance will end up demanding more expensive precious metal for the catalyst. In the extremely cost-effective commuter segment, performance takes a back seat to price. This is why manufacturers seem to be taking the route of bringing the power/torque curves further down in the rev range, which should improve rideability, and also emissions.

So, while the specifications may be a bit lower on paper, the riding experience for the target customer should remain largely the same, or even better in some cases. The giveaway can be found in the spec sheet, where the torque and/or power figures are now being produced at lower rpms. Click here to read more about why the small BS 6 motorcycles engines are losing power.

Content & data copyright: Autocar India

BS6 norms special: part 1 – the background story

BS6 norms special: part 2 – how BS6 engines work

BS6 norms special: part 3 – the engines BS6 killed


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