Re: INFO: A Guide On Technical Jargons

Thank you Samarth.

One more question:

- Can somebody please explain steel braided brakes? What's the difference between them and the regular brakes and how are they better?


I did read a bit on the internet but could not understand much.

Re: INFO: A Guide On Technical Jargons

I wasn't sure whether to start a new thread or not so thought of putting my query here.

We all know what a Fuel Injected vehicle is. In a layman's language there is a Computer (ECU) which controls the Air-Fuel mixture in the combustion chamber. But I wanted to know more about this Fi system. One of the crucial piece of part of the whole Fi system is the O2 Sensor or Lambda sensor.

Now, there are two type is O2 sensor.

1. Closed loop - Like in modern bikes such as KTM, Ninja, CBR, Yamaha
2. Open loop - Pulsar 220 Fi

Here is what I can understand a bit from Wiki.

"Automotive oxygen sensors, colloquially known as O₂ sensors, make modern electronic fuel injection and emission control possible. They help determine, in real time, if the of a combustion engine is rich or lean. Since oxygen sensors are located in the exhaust stream, they do not directly measure the air or the fuel entering the engine but when information from oxygen sensors is coupled with information from other sources, it can be used to indirectly determine the air-fuel ratio. Closed loop feedback-controlled fuel injection varies the fuel injector output according to real-time sensor data rather than operating with a predetermined (open-loop) fuel map. In addition to enabling electronic fuel injection to work efficiently, this emissions control technique can reduce the amounts of both unburnt fuel and oxides of nitrogen entering the atmosphere. Unburnt fuel is pollution in the form of air-borne hydrocarbons, while oxides of nitrogen (NO_x gases) are a result of combustion chamber temperatures exceeding 1,300 kelvin due to excess air in the fuel mixture and contribute to smog and acid rain."

Thus my question is that how an open loop O2 system is different from Carb fuel system as both require manual intervention to set the Fi to a desire level, I assume?
A bit more simple detailed explanation regarding Closed Loop & Open Loop Fi system.

Re: INFO: A Guide On Technical Jargons

You've asked for a long post there Dipankar. All right. First things first - The Carb and the FI are both fuel metering systems and that's where the commonality ends. Its like both I and Bruce Lee are human beings

The FI systems are about very precise fuel metering that is just not possible with a carb however close to the required specification it is made and however well set it is. Because a carb does not have the kind of metering flexibility built into it that an FI system has. A carb uses fixed size jets that allow a fixed amount of fuel for a certain throttle position. And a carb cannot atomize the fuel as well as the positive pressure fed FI systems do. This atomization (breaking up of the fuel stream into a fine vapor cloud) also leads to better combustion which in turn leads to better fuel economy and less environmental pollution. So in a nutshell an FI system is usually better than a carb - the qualifier 'usually' applies to rare occasions where a well set carb gave better control to the rider than a basic FI system did. Such rarity was not as a result of an exceptional carb but due to the primitive nature of the FI system. The 220 is one such case in point.

So much for comparing jack-fruit and oranges. Now to your basic question - the difference between open loop and closed loop FI systems. First a short informal premise on what FI systems are. All FI systems feed fuel in accordance of certain measured parameters of the engine vis a vis the amount of air being sucked in (the Mass Airflow Sensor), the engine RPM, the position of the throttle (Throttle Position Sensor), the position of the crankshaft (Crank Position sensor) and a few other apart from these. The ECM or the Engine Control Module has a microchip that has a 'fuel map' i.e. a table of values that relate the above mentioned parameters to the amount of fuel to be squirted into the combustion chamber. The 'amount' of fuel is actually usually the time duration of the squirt. For example for an engine at 1000 rpm with the throttle open at 79 deg, the fuel map allows for a 7.1 millisecond fuel burst.

Open loop systems are called so because the FI system does not get any feedback about how the fuel it had injected was burnt i.e. whether it was in excess or was less than the ideal. It just feeds fuel based on the results from various sensors and by relating them to a pre-fed fuel map. The difference between this and a carb? The FI system can change the amount of fuel being fed in variance with the variation in outside air temperature, density, humidity etc. In practical sense if you ride from here to Leh, with a carb you need to install a smaller jet to compensate for the lesser available oxygen in the air at high altitude. However the FI system will compensate for that automatically and feed progressively less fuel as you gain height.

Closed loop systems have an Oxygen sensor that tells it whether the amount of fuel fed was correct, less or more than needed. For petrol, the 'ideal' air to fuel ratio is 14.7:1. This ideal ratio is also called the stiochiometric ratio. In the real world there's actually some variation in this value because air happens to be 2/3rds Nitrogen, the fuel is not exactly just one hydrocarbon but a mix of quite a few different compounds. But all said and done, the Oxygen or the Lambda sensor tells the ECU whether the fuel was in the right ratio mainly by measuring the excess air factor (EAF) of the exhaust gases. The EAF is the ratio of the 'ideal' air/fuel ratio to the 'actual' air/fuel ratio. In fact a ratio of ratios! Going glassy-eyed already - hang on, there's more! You asked for it, didn't you?

If this ratio of ratios is a perfect 1 it means that the 'actual' air/fuel ratio is exactly 14.7:1. If less than 1 then there's more fuel than air i.e. the mixture is 'rich' (and you get less mileage), if more than 1 then the mixture is 'lean'. Closed loop systems are more sophisticated than open loop systems, require greater processing power from the installed chip in the ECM and so are more expensive.

Hydraulic brakes work on one basic property of liquids - that they are virtually incompressile under pressure. When you squeeze the brake lever, the piston attached to the lever tries to compress the hydraulic fluid in front of it. The fluid being incompressible, the pressure gets transmitted through the hydraulic lines and reaches the caliper pistons pushing them forward which in turn pushes the brake pads forward into contact with the rotating disc between them. The pads pinching the disc between them causes it to slow down in turn slowing down the wheel it is attached to. The movement of both the lever mounted piston and the caliper pistons is of the order of a couple of millimeters and the volume of fluid displaced is thus also small. Ordinary brake lines i.e. the non-steel braided ones tend to balloon out under pressure and so effectively increase their volume and thus cause a pressure drop in the fluid. The harder the squeeze on the lever the greater is the ballooning. Steel braided brake lines have a fine mesh of stainless steel sandwiched between two layers of flexible tubing. This steel mesh is flexible enough to let the brake line remain flexible but rigid to circumferential expansion. So almost the entire pressure generated by the rider's squeeze on the brake lever reaches the calipers and instantaneously so. Hence better feel and performance of brakes.

Re: INFO: A Guide On Technical Jargons

Sir... many thanks... You did clear a lot of queries! Now, that one small component, called O2 sensor makes all the difference. The reason for me asking the question regarding these 2 different Fi system is that my 220 has to be plugged in to a diagnostics tool for CO setting & while, I believe, the KTM or Ninja doesn't have to be.

Re: INFO: A Guide On Technical Jargons

I was watching Wheelers Dealers on Disc Turbo this Saturday in which an old Brit car, Triumph TR6 was being restored. In one part they mentioned that TR6 was vulnerable rusting of internal parts of coolant system due to quality issues. They flushed the entire system & then used non water based coolant. They explained that even though water based coolants have better tolerance level wrt water but they are not foolproof as water does harm the internal parts in the long run.

My question is how does the modern engine fair wrt the above mentioned issue?

Re: INFO: A Guide On Technical Jargons

Ahem ahem!! Seems like nobody knows the answer??

Re: INFO: A Guide On Technical Jargons

i would like to add my own query to yours, i have seen ppl mixing water in coolant for four wheelers, can we also do so in our bikes (dukes and NS)

Re: INFO: A Guide On Technical Jargons

I will not recommend that. Reason for this & reason for raising the query is that in that program they showed huge amount of rust particles getting accumulated at the bottom of pump!! So, over a period of time the water does affect the system's internal parts!

Re: INFO: A Guide On Technical Jargons

Propylene Glycol was used as a non water based coolant with higher boiling temperature.....but the product is more viscous than Pure Distilled Water, and so not very good in terms of cooling..ie., taking heat away from the engine block ,and ability to circulate faster to enable better heat exchange . Normally the manufacturer of such products don't reveal the contents of the product,so is hard to know who uses what...here are links..

Non-water based coolant - PeachParts Mercedes ShopForum

Evans Waterless Engine Coolants - FAQs - frequently asked questions

Re: INFO: A Guide On Technical Jargons

I've learned a lot from this thread. My 2 years of "engineering" still couldn't teach me all this

Re: INFO: A Guide On Technical Jargons

I think more Torque gives more acceleration, if I'm not wrong. Isn't that's why we accelerate quicker on first gear than on 2nd gear from a stop? Larger gear ratios multiply torque and sacrifice speed, that's why we have to shift up to a closer gear ratio to transmit the same power the engine develops at the crank.

Re: INFO: A Guide On Technical Jargons

And in the later gear, we get more speeds, isn't it? Regarding what you said, yes, we get more torque in first gear, but that's only on the torque at rear wheel. Here, we're not talking about rear wheel's torque, we're talking about torque (or power) at the engine crankshaft. Both these are separated by transmission system and its losses.

Buddy, Power and torque are inherently not that different after all. Torque is just force, with no reference to movement caused. Power includes the movement too. That's why Power = Torque * rpm.

Coming to the point, Acceleration means the increase in speed with reference to a small period of time. In the entire range of rpm, most rapid acceleration is in the uppermost area, right before redline i.e. where the maximum power develops.

In conclusion I can say:

1. running speed depends on rpm, (the speed at 6000 rpm will be double to that at 3000 rpm, isn't it?)
2. force depends on torque,
3. Acceleration depends on both of these (running speed and force) which means acceleration depends on (rpm and torque).... and (rpm x torque) = (power). So, acceleration depends on power. Simple?


So, if you have two machines, both of 600cc and similar/ close configuration but one making significantly more power, then the one making more power will generally accelerate better if you're touching the redline in each gear before shifting up.

I've discussed this topic many times before and in good clarity. Please do search for other topics on "power/ torque" on Xbhp.

Re: INFO: A Guide On Technical Jargons

Nice clarification bro
Yeah I agree on the point of power being relative to torque(I totally missed the formula P=2*pi*N*T/60). Earlier I used to think bigger cc engines give more power, where I was totally wrong. I'm still learning though, so excuse my mistakes

Re: INFO: A Guide On Technical Jargons

[MENTION=11482]Samarth 619[/MENTION] - This reply needs a few inputs to clear thing up. I've added those below.

There is no need to bring in transmission losses, torque values at crank etc for this response. The question put up was simple - is the motorcycle's acceleration more dependent on its torque or power figures?

The engine only produces torque. The turning force. The rotative force. Power is a unit of convenience invented by us to understand and compare engine potential and also what happens when we are past the peak torque RPM. Power is purely a mathematical concept with no physical status. Hard to believe when power is bandied about so much but thats where it stands. Power is as you correctly stated - torque times RPM. In simple terms this means - Increase torque at same RPM or increase RPM at same torque and you get more power.

Acceleration does mean rate of increase of speed over time. But what you say later is not correct. You get a surge of power up in the RPM band (and so feel the greatest acceleration) usually because there is a simultaneous increase in both the torque and the RPM which produces a large additional force in that given time period. The 'acceleration' felt through the seat of the pants is actually a change in inertia - one moment you're sitting upright on the bike and the next it is throwing you back as it pulls ahead hard and you have to hang on to the bars. This change in inertia was brought about by an increasing turning force pushing the bike faster through its rolling tyres. Power would just be a value - it is torque that is doing the pushing.

The utility of power comes in engine tuning. Usually you see peak torque quoted at a lower RPM than peak power. Thats how most engines are tuned. (There are exceptions though in very large displacement cruiser engines or drag bike engines that just need as much turning force as can be handled by the available traction. ) Coming to typical engine tuning, we continue to accelerate even after the engine RPM is past the peak torque value because the increasing RPM's compensate for the decreasing torque. The power output continues to increase till the RPM's increase at a faster rate than the torque dropping off. Which is why beyond a certain RPM (the peak power RPM), revving more doesn't bring about any further increase in acceleration. This RPM limit is usually the result of the limits to engine breathing ability.

#3 - The acceleration not just depends on torque but also on the gearing.

Drop a couple of teeth from the Duke 200 rear sprocket and I doubt if you'll get those sub-10 sec 0-100 kph timings. Same engine, same torque, same power - just the gearing is different. The gearing defines how quickly those RPM's increase. That 'rate of increase of RPM's is translatable to a rate of increase in torque and so power. So the quicker the RPM's build up, the faster will be the acceleration in absolute terms. Of course if the gearing is so low that you run out of available RPM's every 10 kph, then a comparable bike which gives an increase of say 30 kph for every shift will get to 100 quicker because you'll be wasting lots of time in shifting gears on the lower geared bike.

A simple adage defines the difference between torque and power - Power needs RPM's for its existence while torque is the beginning. Remember the mixer-grinder at home - peak torque at zero rpm! Torque is a turning force, a primal manifestation of energy while power is just a measure of convenience. You need 22 ft-lbs of torque to unscrew your bikes wheel nut and that torque value is breached the moment you feel the spanner turning. With the turning of the spanner was born the measure of power.

I guess I am getting a little carried away now .

Re: INFO: A Guide On Technical Jargons

[MENTION=10597]Old Fox[/MENTION]: Sir, you have this amazing ability of putting down concepts in words. Very well explained. Having the clarity in your mind is one thing, and penning it down in words is totally another.
My wordings being inaccurate, all the lines of your post perfectly coincide with my thoughts, except one though, where I know I typed wrong, as I got confused on what Divyanshu asked:- Is the torque in first gear actually higher than that in the second gear, assuming same rpm? That's when I thought about torque at crankshaft and torque at rear wheel, thinking that the torque in first gear (at rear wheel obviously) is definitely more because the first gear can actually drag heavier loads..(?)

I thought about it for some time and I guess I came up with an answer:-> Torque is a certain amount of force that can be put to work.
Shorter Gearing makes the torque do lesser work so it does so easily, with eagerness. Longer gearing makes it do more work, so the pressure starts to show.
So, basically at a particular rpm, the torque is same but you're making it do more work in higher gears, and hence it doesn't push with the same zeal. I guess?


Had to think about it for a lot of time though... Being in Commerce field wasn't of much help either, getting these scientific theories. So Sir, did I get this correctly now?


PS: Of course, transmission losses don't come in the picture here. Just mentioned it in my original post as a side note.

I think you wrote this line the opposite of what you meant.... Because in the rest of the paragraph, you mentioned how overgearing will benefit Duke when it comes to 0-100.
Even I felt the exact same thing, when I saw its performance figures.

It does a 100 kmph in fifth gear, with fourth gear topping out to a close 98~ (IIRC).
It does a 60 kmph in third gear, with second gear topping out at 58~. Real speeds here.

Even putting a 42 or 41 teeth sprocket should see an improvement in both 0-60 and 0-100 instantly, as it will touch them in 2nd and 4th gear, with hardly any drop in the roll on. But maybe, they were focusing more on city riding experience than journalist feedback. Either ways, gearing it too short wasn't the best decision I feel.