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Carburetor Vs. Fuel Injection [Myths & Facts]

Carburetor Vs. Fuel Injection

The other day one guy quizzed me about the expected fuel efficiency of the KTM 200 Duke. I told him that I can’t tell for sure but it can be expected around the 30 Kmpl figure.

That guy was surprised and told me, “That low..?? But the KTM 200 Duke has Fuel Injection, so why such a low mileage figure?”.

I wouldn’t blame that guy as there are many myths surrounding “Fuel Injection” system. Till a couple of years back, even I used to think that "Fuel Injection" was a magic pill which elevated a bike's performance dramatically.

Fuel Injection: Myths

Myth 1: Fuel Injection gives a drastic increase in mileage (fuel efficiency)
Myth 2: Fuel Injection gives a bump in Power
Myth 3: Fuel Injection gives a much better throttle response than a carburetor

In theory a Fuel Injection system should improve the fuel efficiency, power delivery and throttle response. But after having ridden numerous motorcycles over the years both with carburetor and with Fuel Injection, also having owned a fuel injected motorcycle (Pulsar 220 DTS-Fi), I can tell with conviction that the above benefits of “Fi” are hardly tangible to the rider.

A well tuned carbureted motorcycle also returns equally good fuel efficiency, can deliver same power and once warmed up the engine can feel same in operation.

How a Carburetor Works: In Simple English

How a Carburetor WorksA carburetor is a mechanical device which mixes the fuel (petrol) from the fuel tank with air from the atmosphere and sends this mixture to the engine for combustion.

The movement of the piston inside the engine creates a low pressure and this “sucks” the air + fuel mixture inside the engine, which is then ignited for making power.


Advantages:

[+] Cheap to manufacture

[+] Easy to service

[+] Performance modification can be easily done on it

[+] Tolerant to bad quality fuel

[+] Not dependent on a battery / electrical charge


Disadvantages:

[-] Need to apply choke during cold starts and need to warm the engine for a steady idle

[-] Need to adjust the settings when the altitude changes

Fact 1: Fuel Injection is costly

Price differential between a Carbureted and Fuel Injected variant of the same model currently in India is around Rs. 15,000-20,000 (Eg: Carb and Fuel Injected variants of the Hero Glamour, Honda CBF Stunner, TVS Apache RTR 160). As I mentioned earlier, the fuel injected variants hardly give an increment in either power or fuel efficiency despite the price premium.

So why is actually Fuel Injection required?

Once upon a time all petrol cars sold in India used to run on Carburetors, currently all petrol cars have shifted to Fuel Injection, so when did this shift happen and most importantly why?

The shift from Carburetor to Fuel Injection in Indian cars started in the mid 90’s and by 2000 nearly every model was running on fuel injection. So, why did this shift happen? Govt. of India was pushing for strict pollution/emission norms, therefore it became impossible for the car manufacturers to comply with the emission norms with carburetors and the only solution was to opt for Fuel injection. I still vividly remember that the cost differential for switching from Carburetor to Fuel Injection in a compact car like the Maruti-Suzuki Zen in the mid 90’s was around Rs. 30,000. The car manufacturers had no option but to swallow the bitter bill and go ahead with the costly tech.

Therefore..

Fact 2: Main benefit of Fuel Injection is conforming to strict pollution/emission norms

But the catch here is that unlike 4 wheelers/cars, 2 wheelers/motorcycles can still conform to the pollution norms set by Govt. of India with a much simpler and cheaper carburetor without the need to go for Fuel Injection and would not require very soon in the near future as well.

After spending a premium for this "costly and clean" technology, isn’t there some tangible benefits to the rider who opts for Fuel Injection on his bike?

There are two tangible benefits..

Fact 3: Fuel Injection gives a hassle free early morning/cold starts and adjusts to change in altitude automatically

Fuel Injected vehicles (cars and bikes) don’t have a “choke” lever. It doesn’t need one. The electronics and sensors take account of the conditions (amount of oxygen, temperature etc.) and accordingly inject the correct amount of “air+fuel” mixture to the engine every time. For this reason one doesn’t need to worry for cold morning starts and there is no need to warm the engine as well. Also one doesn’t need to worry about changing the “air+fuel” mixture manually (like changing the carburetor setting) when the altitude changes.

From my own of experience of owing a car and motorcycle with Fuel Injection (Pulsar 220 DTS-Fi), I can share that all one needs to do is to switch on the ignition to start the engine with a single crank and just zoom off.. every single time.

How Fuel Injection Works: In Simple English [Photo: World Honda Site]

Fuel Injection on a MotorcycleA Fuel Injection system consists of many components. One of them is a fuel pump which resides inside the fuel tank. This device pumps fuel to the injectors which according to the signal from the ECU "injects" the optium amount of "air + fuel" mixture to the engine.

There are many electronic sensors like oxygen sensor, temperature sensor working with the system which sends signals to the Electronic Control Unit (ECU). The ECU is programmed to work under variety of inputs and conditions. It is the heart of the Fuel Injection system which controls the inputs to the motorcycle for an efficient, clean and hassle free combustion of the "air + fuel" mixture.

It is hardly surprising why a Fuel Injection system is heavy on the pocket.

Advantages:

[+] Very effective in controlling pollution
[+] Hassle free cold starts and no need to warm the engine for a steady idle
[+] No need to change settings to ride at different altitudes

Disadvantages:

[-] Costly
[-] Sensitive to bad quality of fuel
[-] Needs specialized equipment for service
[-] Always dependent on a battery (with good charge) for operation
[-] For Performance modification the ECU would need to be re-programmed..!!

Fuel Injection & Indian motorcycles:

Expecting customers delighted to pay Rs. 15,000 more for fuel injection when the cost of the vehicle is Rs. 60,000 just for hassle free early morning starting would be wishful thinking.

But then there are other type of customers who are ready to buy bikes costing Rs. 1 Lakh (1,00,000) plus. Such a customer I guess would not mind paying a premium for a hassle free ride experience. Personally I would definitely want to have Fuel Injection on my motorcycle.

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