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I recently bought the new kawasaki ninja 1000 sx 2020.....i wanted to try until how much the reserve petrol tank will hold....the range shown in the display was the only thing I was relying on....but as of now its showing only this - - - km. And its blinking in reserve ...anybody has any updates on this or knows anything regarding it ...pls do help
 

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A Black 2019 N1K
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I may be wrong, but I am reasonably sure that the N1K does not have a "reserve" petrol tank.

I am also not sure if this covers your situation, but it seems that from 2020 Owners Manual, which I am sure your Dealer gave to, that you have less than 4 litres of fuel left in the tank.

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What @Murphyau said, there is no separate reserve tank, at least for the 17+ model. The range shows two dashes when 13.5 litres is consumed, leaving another 4 litres that you can use to reach the nearest gas station.
 

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My experience is that the range indicator is very accurate. In 51000 miles its never been wrong.
I even knew once that my laps in attention was going to leave me a few miles short of fuel and it did. The triple horizontal bar (---) on mine comes on around 20 miles remaining.
 

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While I don’t think any bikes today actually have a reserve as in the old days, I still see the term used loosely as the amount left when a low fuel indicator come so on.

As to range, that is the one thing that changes based upon your fuel mileage for some period of time or miles - like maybe the last mile for example. I never look at range for that reason. I reset my trip odometer and average fuel mileage every time I get gas. I use those to determine how much I have left.
 

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Like Avintage69, I've found the fuel indicator very consistent. It's not linear (e.g. each bar does not represent a similar amount of fuel), but it is consistent over the years and miles. While that is true, on my 6 bar scale, I have 1/2 tank when it goes to 3 bars. Also, when it begins to flash, indicating it's electronic "reserve" is reached, there is 1.1 gallons left. I know if I'm gentle, I've got 40 miles left. I also use a trip meter for my "fuel gauge", resetting it with each fillup.
The "range" indicator works well enough IF you're riding fairly consistently. I think I read it takes the average fuel use of the last 20 seconds to use in it's calculation.
The big Ninja engine can suck in a lot of fuel if you flog it and does well if you're just cruising. I've seen anywhere from about 30-50 mpg on my Ninja.
 
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'20 Kawasaki 1000SX, '18 KTM Super Duke R, '16 Yamaha FJR1300ES
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While I don’t think any bikes today actually have a reserve as in the old days, I still see the term used loosely as the amount left when a low fuel indicator come so on.
Yes, I remember my old '72 Norton that had 2 fuel petcocks on the bottom of the tank, one on the left for the regular tank and one on the right for the reserve tank. No fuel gauge--when the bike started to sputter you had to quickly reach down and turn on the reserve valve and then start looking for gas.
 

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I trust the N1K's Fuel gauge, but I am not sure I trust the "Range To Go" readout. I have always kept a fuel log on my trips, so here is my data for the only two rides on my N1K that I have done this year. ( damn you "covid" )

Across 1,905 kms of combined highway & back-country roads, I have averaged 20.6 km/l (48.4 mpg), with a "high" of 22 km/l and a "low" of 19.0 km/l.

So now, I know that at around 300 kms (15 lt) I should be looking for a fuel station. Easy pessie.

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You guys know what the sending unit, for the fuel gauge looks like, right? My new toilet has a float that's more sophisticated.

When you see this float, imagine the internal shape of the fuel tank. This is why the whole idea is not much more than a joke. With the round sections, angled, and square shapes, you'll never have a accurate way to measure volume.
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<< snip >>
When you see this float, imagine the internal shape of the fuel tank. This is why the whole idea is not much more than a joke. With the round sections, angled, and square shapes, you'll never have a accurate way to measure volume.
I'd have to disagree with you there RC. A fuel tank could have 1,000 irregular sides and the fluid inside will always have a level surface (simple physics) and the fuel float will be accurate. The only exception would be if 1 side of the tank was lower then the other, which is not the case with the N1K tank.
 

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I'd have to disagree with you there RC. A fuel tank could have 1,000 irregular sides and the fluid inside will always have a level surface (simple physics) and the fuel float will be accurate. The only exception would be if 1 side of the tank was lower then the other, which is not the case with the N1K tank.
An irregularly shaped tank will make the float readings non linear (as opposed to a cube)--I doubt that the fuel gauge accounts for this.
 

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If the ECU has enough "computing power" to make to make multiple "on the fly" calculation every second for the fuel mix, based on air temp, rpm, throttle position, etc, it has more than enough "computing power" to calculate fuel volume ever 2 seconds based on 1 know fact ( total fuel tank volume) and 1 variable fact (float vertical position).
 

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Murph, You are right about that, but think of it like this. Stand in back of our tanks and look at the shape. The liquid will be flat, but think of how much liquid has to be removed to drop the level 25mm. Its the same reason we **** bricks when we have a hospital call in and say their liquid oxygen level is at 12 inches, on a normal 1500gal, horizontal tank. At 24 inches, they have about 4x more volume than they do at 12.

Lets fill this 100% with no head space. At the top, a 25mm drop wont need to have much liquid to be removed. Towards the middle, you need to remove more for the same 1 inch drop. You could calibrate the float, for this tank in the picture, but not so much for our gas tanks. This fuel pump is used in many different models.

You can calculate this on around cylinder, but not so much when you get into the tapered shapes like our tanks. The floats a
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e our tank has.
 

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Murph, I think an exact calculation could be made, but it would need to know exactly how much fuel you added and have some other, more exact way to know just how much is there. I always thought they could use weight? My only point was we are lucky it's as good as it is.

I know my bike stays at full for the first 30-40 miles, then drops like a rock during the next 40.

The article here brought up a good poi t when he said the float cannot go to the top of the tank. It makes sense that the float would not know if you put enough fuel in to reach the floats top stop, or you failed it right to the neck. My bike is bad for this. It's a california tank so it will hold a half gallon more than it appears to if you judge full by the fuel neck.
 

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Please excuse the crudity of the drawing, but it represents a stylized fuel tank, with the dimensions (mm) in blue.

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High School math will show that the volume of Z = 30,000 mm*3, Y = 48,000 mm*3, U = 18,000 mm*3, X = 9,000 mm*3 & V = 9,000 mm3. The total volume (Z+V+U+Y+X) is therefore = 114,000 mm*3.
  1. When the fuel float is at point A, the tank is 100% full and for the sake of my argument equals 19 litres of fuel.
  2. When it is at point B, the remain volume is (114,000-30,000)= 84,000 mm*3. This equates to 74% (84/114) or 14.1 litres.
  3. When the float is at point C, the remaining volume is (114-30-9-18-24)= 33,000mm*3. This equates to 29% (33/114) or 5.5 litres.
  4. When the float is at point D, the fuel tank is empty.
The ECU monitors the fuel float position as it moves along the path A-B-C-D and can easily perform the math to determine what the remaining fuel volume is, just as easily as I have in this example.

It knows the maximum volume of the tank (fixed) and it knows the position of the float (variable), the rest is simple math.

As for the "Range To Go", once the ECU knows the volume of fuel in the tank, and knows what rate it is injecting fuel into the engine, it is again simple math to calculate the estimated range.

For example, if I am traveling at 100 kph, and using 100 ml of fuel per minute and I have 10 litres of fuel in the tank, my estimated range is 167 kms. ((10,000/100)*100/60)
 

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Murph, I know your formulas are accurate. We have problems because the section you have marked "z" doesnt have a defined volume. That's user controled. If my bike is the example, it will hold 1/2-3/4 us gallons more once the fuel level is at the bottom of the filler neck. The float, or ecu has no idea if I did this heavy fill, or stopped at the neck for a normal fill. That's an extra 30-40 miles of range the system cannot account for. For people following along, dont do this extra fill if you still have your california emissions stuff in place. When the fuel gets hot, it expands and will push gasoline into your charcoal canister.

With that said, look at how accurate our fule gauges are. The proof of what they know, and dont know, is shown in their actions. They are fairly accurate, but most riders who dont care to run out of fuel will be watching the odometer as much as the fuel gauge. We also have a lot of tipping, leaning, and changing motions to deal with that makes accuracy suffer.
 

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The ECU monitors the fuel float position as it moves along the path A-B-C-D and can easily perform the math to determine what the remaining fuel volume is, just as easily as I have in this example.
The question is, does the ECU actually perform these calculations for varying volume segments or just use an average. I'm inclined to think it's the latter and therefore the fuel level per the gauge and the estimated range are not always completely accurate.
 

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Murph, I know your formulas are accurate. We have problems because the section you have marked "z" doesnt have a defined volume. That's user controled.

If my bike is the example, it will hold 1/2-3/4 us gallons more once the fuel level is at the bottom of the filler neck. The float, or ecu has no idea if I did this heavy fill, or stopped at the neck for a normal fill. That's an extra 30-40 miles of range the system cannot account for.
That is a correct statement. My guess is that when the tank is "over filled" the ECU will default to 100% full until such time as the float sends a signal that equates to 99% full, then the ECU will start to do an accurate calculation.

For people following along, dont do this extra fill if you still have your california emissions stuff in place. When the fuel gets hot, it expands and will push gasoline into your charcoal canister.
Again, another correct statement.

With that said, look at how accurate our fuel gauges are. The proof of what they know, and dont know, is shown in their actions. They are fairly accurate, but most riders who dont care to run out of fuel will be watching the odometer as much as the fuel gauge.
Again, another correct statement. As I mentioned above, I trust the Fuel Guage but not the Range Estimate. I know that my N1K gets 20 km/l on average, so it is simple to just reset the Trip A odometer when I fill the tank, and then do the calculation in my head (distance travel / 20 = fuel in litres used).

We also have a lot of tipping, leaning, and changing motions to deal with that makes accuracy suffer.
When the bike is moving, centrifical force tends to slow the movement of fuel down, but I take your point.
 

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The question is, does the ECU actually perform these calculations for varying volume segments or just use an average. I'm inclined to think it's the latter and therefore the fuel level per the gauge and the estimated range are not always completely accurate.
The ECU has many sensors that monitor activity in real time, not "average time". An example is the throttle plate position sensor or the front/rear wheel motion sensor. There is no reason to believe that the ECU could not also monitor the fuel float level in real time.
 
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