Feb 6, 2012

30 Carburetor Vs. Fuel Injection [Myths & Facts]

What is the real benefit of using Fuel Injection instead of carburetor.. what are the tangible benefits of 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

A 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.


[+] 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


[-] 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?

One 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.


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.


[+] 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


[-] 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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This is to remind that the Views or Opinions in the blog are entirely mine unless explicitly stated. The Views and Opinions published in this blog should in no way be related to any other person or organization associated -- directly or indirectly -- with me.


ketan kadam said...

but both do the work of sending fuel to the engine so how is pollution controlled actually?

Anonymous said...

hi payeng bro.thanks for sharing such a valuable information.i am a silent viewer of your blog and i must say that you are doing a pretty good job.keep it up.waiting for pulsar 200ns test ride review.

S.P - Biker Next Door said...

@Above, thanks bro

@Ketan, I am no mechanical engg. but in "Fi" the "air + fuel" is is supposed to be optimum, minimizing the wastage of fuel also there are a lot of sensors attached to the "Fi" system

Rahul Devnath said...

Satadal, this was one overdue post, kudos for putting up here. I'm sure every desi biker, has this question in mind today. More so after the fact that the nextgen Pulsar will still carry on with the humble Carb as opposed to an FI! From my experience I can comfortably say that carb bikes would not bother you much even at sub zero temperatures! Indeed Fi will start better off. But is their point in paying 15K more for just this benefit? I guess most poeple will not but some may. It's same thing when people would like to spend another 5K just for a projector headlamps alone (though they have a tangible benefit). But as the saying goes "if it ain't broke, don't fix it". Over and above that Carbs delight an enthusiast who would like tinker around. Also, even in current Indian biking scenario, Carbs tend be far more reliable; blame it on humid and dusty conditions or sub standard fuel in our country. Carb it is!

Anonymous said...

Hi buddy,
Please also comment on the myth "It is harder to steal petrol from a fi bike as the small pipe from tank is not there".

Thanks for the informative post.:)

Anonymous said...

hey bro nice topic to write on.. seriously now i understood de difference between both..keep writing on such interesting topics

Veerendra Giddaluru said...

Interesting article there, with Pulsar's triple spark tech, guess Bajaj is taking reverse route to confirm to pollution norms. Instead of going for FI to inject optimum air+fuel mixture, they are looking to burn whatever is taken into engine via carb using three spark plugs.

Shaiju B said...

Nice article Payeng. This is the differentiating factor for you. Expecting more such articles from you. Best Wishes.

Still wondering paying a premium of 15- 20 k is worth it ?

shekhar said...

@Satadal very rightly said bro.........i have ridden my bikes both fuel injected and carburated ....and i own honda dazzler.....trust me never have i felt the need of having a fuel injection.....it still provides awesome mileage, throttle response and performance.....wonder how much increase would have been there if it were fuel injected....
good move by bajaj also for having a carburated engine in the 200NS.......
HONDA STUNNER PGM-FI.....it does not just because of its high price....... else its an awesome bike.....

S.P - Biker Next Door said...

@Rahul, Veeru, shaiju and Shekhar thanks for sharing your views..

But all said and done, one a guy is "spoiled" by the hassle free experience of Fuel Injection, its difficult to come back to carburetor.

For Example, it would be nearly impossible for anyone to imagine driving a car with a Choke and Carburetor.

But yes, whether Rs. 15K premium is justified on a motorcycle or not is a matter of debate.

Anonymous said...

Very interesting article.
BTW, I owns two bikes in same engine size, one with single spark plug (Honda Shine) & double spark plug (Bajaj XCD 125). But, I never felt any notable difference in engine performance, rather than XCD has very little more pickup. Even Shine returns me better FE. So pls throw light of knowledge for single spark plug, double or triple performance. Does double spark plug really make difference in FE & performance figures? or its just a marketing gimmicks?? If 2/3 plugs in single cylinder really made such change (as claimed by Bajaj), why didn't other manufacturer in the world (Pls note, I m not referring to domestic TVS or RE)not using it?
Its very hard to rely on the truth that the Germans, who are the magician of engines, not opted for this Technic in last 100 yrs???

Anonymous said...

Cars have minimum 3 to 4 cylinders. All bikes made in India are single cylinder. Cars with multiple cylinder engines work more efficiently with Fuel Injection. For bikes with single cylinder, carb is enough.

But still, carburetor bikes should have additional kicker. While fuel-injected bikes do not need kicker.

Multiple spark plugs for a single-cylinder bike only increases chances of misfiring.

ranggantengblast said...

"Fact 1: Fuel Injection is costly "??
well, in Indonesia the difference in price isnt that much. ex: pricing for scooter honda spacy carburetor vs spacy pgmfi only about $25 difference. another example s like yamaha vixion(FI)about $2400 vs yamaha byson (FZ, carburator) about $2300

Anonymous said...

hmm...author so desperate to prove pulsar 200ns is better value for money thn ktm200 duke

Crash said...

The truth is carburettor is just old school though said to be reliable and proven is no match for fuel injection. FI is the way forward and is much more advanced with space age technology incorporated to it. In reality FI is like a 4 stroke engine while carburettor is like a 2 stroke engine.

Anonymous said...

well whoever wrote this article is misleading everyone , Dude seriously after reading your article i am just pissed on guys like you who ride pulsars and think they are the gods of the roads................. try comparing the FI units of Honda or Yamaha with the Pulsar u will know the diffrence and the myths ....

S.P - Biker Next Door said...

@ the guys pissed over "Pulsar": Take a Chill pill and get a Life.


Anonymous said...


Parthiban .R said...

thank you for giving me difference between the fuel injection and carburetor

GAUTAM said...

Thank you n I really appreciate your work on this topic, very informative..! keep going..!
and pls let us know what actually made YAMAHA to Stop their RX135 or RX135 (5 Speed) models.
Expecting an article on PROJECTOR HEADLIGHTS.! Thanks in advance..!

Amol said...

Who says that there is not any tangible differance between carb & fi bike. I have driven pulsar 220 FI & pulsar F(Carbed).
Lot of differance is in engine note,power delievery,nvh level. FI bike is always fun to drive.

Anonymous said...

HI, it is a good article, thanks for the information.. I am a pulsar biker from Indonesia.


balaji said...

Hi, It is a good article..
I got a question..

Like u said KTM duke 200 delivers only around 30kmpl. But enfield bikes which has carburetor and 350cc engine, it delivers around 40kmpl.

Enfield has more cc and carburetor how it deliver more mileage when KTM duke is fuel injected and less cc?

why it is so??

Anonymous said...

@Balaji it counts with RPM and BHP of the bike
As the BHP goes up the power too !! and gulps more fuel which results in..!!

Anonymous said...

Hassle free cold starts ? this is not true bro.i own glamour efi and it has a cold start problem.goda fix it

Anonymous said...

Hey guys!!i own a karizma zmr...its fuel pump was giving me a lot of problem...i took my bike to hero service centre ...they told me that the fuel pump motor is not working so it has to replaced...worth of a fuel pump is 14000 rs...and the disadvantage of replacing the fuel pump is that it will have problems every 2 or 3rd year soo i went to other mechanics they told me to replace the fuel pump with carburator system...please help me.out which bike carburator will work in my zmr.....

Yogesh Raj said...

In fi system engine vehicles the battery is not present is it run or not

Yash said...

very good article. I wanted to know if the 4 wheeler's in INDIA still used carburetor (Thats what I studied way back in '94)
Overall good article friend. Thanks for info. You answered my query

Shivakumara Shivu said...

good job.. it will helps at any time to every-one
im happy ro get information and thank you very much to your whole team..

Jithin Shaji said...

Thkx good learning

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