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I know that all speedometers are off, so I've learned to use my gps. I understand that the fuel gauge is inaccurate and I set the trip odometer. I can live with the range estimate jumping around by 50+ miles in a matter of seconds. But they can't even correctly calculate the avg mpg? Every time I fill up it tells me my average mpg is ~41 mpg, but when I do the math based on the trip odometer it is really ~33-34. That's quite a difference. This is running 91 octane with Ivan's ECU mod and K&N air filter in stock box.

Bike is still a new to me 2012 Voyager that only had 1800 miles. I've since doubled that and have read some posts saying that mileage will improve a little as the bike gets worn in but I keep seeing people saying that they can get close to 200 miles on a tank.
 

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This brings up an interesting question for me: How does the software work for the bike in determining MPG? My bike is too old for any of that modern stuff. I have to LOOK at the starting and ending odometer readings for distance and the gas pump to see how much I pumped in. Then its pen/paper/calculator time.

I've never really thought about this but how can the bike possibly tell you at all (forget about accuracy, how can it do this at all?)? When you gas up, do you have a routine of buttons to push or data to enter? I don't think I've ever heard anyone talk about something like that before.

Even my pen/paper/calculator method depends on my odometer readings which are off by 5% or so. Your bike MPG readings are off by a lot as compared to what you figure it to be. Does the ECU flash mod mess with that stuff or does this normal inaccuracy come from the manufacturer?
 

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If I am consistantly running 65 mph or less on the freeway on a full tank and it is flat, I get about 45 mpg both on the dash and doing a calculation at next gas stop. But on road trips out on the flats in MT and WY, that 65 quickly turns into 85 or 90 mph and gas mileage drops way down in the mid to low 30's. 2016 Ivanized but otherwise bone stock Voyager...15K miles.

I'm just kind of used to how far I can go when the FUEL light starts flashing based on how fast I am going. About 1 1/2 gallons left at that point.

Enjoy! And have some Heywards or Gates or Smokestack BBQ for me sometime. We lived for 9 years Gladstone, Grandview and Olathe. Office on College Blvd. OP KS.
 

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I know that all speedometers are off, so I've learned to use my gps. I understand that the fuel gauge is inaccurate and I set the trip odometer. I can live with the range estimate jumping around by 50+ miles in a matter of seconds. But they can't even correctly calculate the avg mpg? Every time I fill up it tells me my average mpg is ~41 mpg, but when I do the math based on the trip odometer it is really ~33-34. That's quite a difference. This is running 91 octane with Ivan's ECU mod and K&N air filter in stock box.

Bike is still a new to me 2012 Voyager that only had 1800 miles. I've since doubled that and have read some posts saying that mileage will improve a little as the bike gets worn in but I keep seeing people saying that they can get close to 200 miles on a tank.
The displayed MPG is based on the estimated rate of fuel consumption from moment to moment. The rate of fuel consumption rate is estimated by the ECU based on current conditions, but it is just that, an estimate. If you have any accessories that draw significant power, you will use a bit more gas and ECU will underestimate the amount of gas you are using. If you are a large person, such as myself, it will underestimate the amount of fuel needed for the given engine rpms and gear. Riding in hills vs flats will affect the estimate. Lots of reasons why it is inaccurate. I have yet to see a motorcycle or auto mpg estimate that was anywhere near accurate and most give a significantly higher value than what you are really getting.
 

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Bikes no different than cars displaying the same "calculated mpg".
I'm guessing they are not right on but close. At least my car seems about right.
If you wanted to be sure do the math at fill ups.
 

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Discussion Starter #6
I have never actually checked my car's avg mpg since it is less than an issue when I can get 440 miles on a tank. And I don't want to sound like I'm complaining, it's just my sarcastic nature when I look at all of the gauges and readouts that I now have compared to my 900 and got to thinking about how the radio is the only readout that seems to be accurate, lol. Looking forward to putting a lot more miles on the Voyager.
 

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Why does the rate of drawn power by electrical accessories affect MPG?
 

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When i got my voyager a little over a year ago i felt the same way and i think its a shame that i have to resort to using my trip gauge to get an accurate miles left in the tank estimate. I did that in the 1970's with my first bike. The estimated miles to empty does jump 30 to 50 constantly and is totally useless. Theirs no excuse for that. I get in the low 40's on mileage so when i put 50 miles on the bike the gas gauge should not show half full, totally useless. 2 gas gauges and both useless. I guess you can see this is something that really aggravates me.
BUT this is why i like my voyager, i looked at a used Indian Roadmaster for $20'000.00 Then a used Harley around $25'000.00 then bought a 1 year old Voyager with 2000 miles on it for $12'200.00. So I'll deal with the little things and know i have a better more dependable motor between my legs when i'm 5 states away from home.
 

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I think

Why does the rate of drawn power by electrical accessories affect MPG?
That there is an increased resistance from the alternator. I mean the extra juice has to come from somewhere since " there ain't no such thing as a free lunch" ( Robert Heinlein ) :wink2:
 

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just curious

I know that all speedometers are off, so I've learned to use my gps. I understand that the fuel gauge is inaccurate and I set the trip odometer. I can live with the range estimate jumping around by 50+ miles in a matter of seconds. But they can't even correctly calculate the avg mpg? Every time I fill up it tells me my average mpg is ~41 mpg, but when I do the math based on the trip odometer it is really ~33-34. That's quite a difference. This is running 91 octane with Ivan's ECU mod and K&N air filter in stock box.

Bike is still a new to me 2012 Voyager that only had 1800 miles. I've since doubled that and have read some posts saying that mileage will improve a little as the bike gets worn in but I keep seeing people saying that they can get close to 200 miles on a tank.
Since the speedo is off and the distance traveled is an estimate and I find it hard to fill the tank EXACTLY the same each time and even though the gas station pumps read the thousandths of a gallon are they truly accurate? What makes you think that the pen and paper method is accurate ? As long as I have cash or card I am gonna gas up and ride and if for some unexpected reason I do run out of gas then the money I pay AAA won't be wasted...:devil2:
 

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Why does the rate of drawn power by electrical accessories affect MPG?
The more amps you pull, the stronger the magnetic fields in the stator, making it harder to turn. The engine has to work harder to turn it, so more gas used. Amps are provided on demand, they are not constant. Just one of possibly several factors that would cause the estimated mpg to be off.
 

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When i got my voyager a little over a year ago i felt the same way and i think its a shame that i have to resort to using my trip gauge to get an accurate miles left in the tank estimate. I did that in the 1970's with my first bike. The estimated miles to empty does jump 30 to 50 constantly and is totally useless. Theirs no excuse for that. I get in the low 40's on mileage so when i put 50 miles on the bike the gas gauge should not show half full, totally useless. 2 gas gauges and both useless. I guess you can see this is something that really aggravates me.
BUT this is why i like my voyager, i looked at a used Indian Roadmaster for $20'000.00 Then a used Harley around $25'000.00 then bought a 1 year old Voyager with 2000 miles on it for $12'200.00. So I'll deal with the little things and know i have a better more dependable motor between my legs when i'm 5 states away from home.
The estimated miles to empty is based on the estimated gas consumption and on the gas level in the tank. The gas level is measured by a float. If you go up and down hills, the float will move up and down as the level of gas in the tank shifts. If you fill higher than the float can go, it will estimate the miles to empty wrong. I have never seen a vehicle that did not have wildly changing miles to empty readings.
 

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As far as gas pump accuracy goes I think they have to be calibrated but I've not a clue as to how often. Even with the pen/paper/calculator method you can only be as accurate as your inaccurate speedo/odometer allows you to be.

As for the increased resistance from the alternator, I still don't see how that matters at all in regards to MPG. Unless you run a TON of electrical doo-dads that pulls juice from the spark plugs how can it affect MPG much less be in the same universe as trying to determine MPG? Or is this an ECU-thing where if it gets too little juice to its brain it goes all weird in engine timing etc. etc.? (I'm happy that mine doesn't have an ECU.)

Apparently, there is some basic working theory and mathematical equation the ECU uses that I'm not grasping. When I figure MPG I take the amount of physical gasoline I filled up with and that figure is divided into the number of miles I've ridden (which will be off by perhaps 5% or so). This divided by that equals MPG. Its a pretty simple equation. What would any possible equation using current flow as a replacement for distance driven and/or fuel used even look like?

Current flow should mean squat. Which seems to be the case since everyone gripes about their bike being so wrong in the results it displays.
 

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Sabre-T you added your last two posts while I was typing my last one. So the bike uses the float as the method of determining gas usage??? I don't doubt your statement at all but that seems to be a built-in problem right from jump street. If I had to depend on the accuracy of the fuel tank float or the accuracy of a gas pump at a station, I'll always go with the gas pump, hands down.

How does the speedo work on ECU bikes? Is it some electrical thing, too? Mine is driven by the front wheel RPMs so its a physical input.

LOL, this conversation is making me less and less trust newer bikes.
 

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Without being an electrical engineer or a bike mechanic i will just use common sense. I have owned cars with the estimated miles to empty and a running miles per gallon and they never ever jump around as some have stated and as for motorcycles i rented the Indian Roadmaster and put a little over 1000 miles on it and it also never ever jumped around and i can assume other manufactures have also figured out how to make this work. The float jumping around just seams like 1960 technology and the electrical draw is a non starter the bike puts out plenty of juice to handle add on's not to mention its own on board systems. I like my voyager and I'll keep it but lets just admit it Kawasaki installed a very low quality system and had 10 years to fix it.
 

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Discussion Starter #16
Since the speedo is off and the distance traveled is an estimate and I find it hard to fill the tank EXACTLY the same each time and even though the gas station pumps read the thousandths of a gallon are they truly accurate? What makes you think that the pen and paper method is accurate ? As long as I have cash or card I am gonna gas up and ride and if for some unexpected reason I do run out of gas then the money I pay AAA won't be wasted...:devil2:
Given that both the manual calculation and the bike's avg MPG are using the same inaccurate speedometer, that should not effect the equation. While obviously you can't always gas up to the exact level every time I wouldn't think the difference would create much variance there either.

Since the two methods (bike's avg vs. paper calculation) are off by 7-8 mpg, that is almost a gallon of fuel difference considering a 5.3 gallon tank. :surprise:
 

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I've not actually checked this, but I've heard that the odometers are correct (federal law) even though the speedometer is not. I've done the calculations at the pump a couple of times and it has come out to with in 1 mpg of what the bike says.

I saw a report a few years ago where they did a test on several different cars to check the accuracy of the distance to empty. Some cars went over 100 miles after they said 0 miles to empty. So I don't put much faith in the accuracy of those.

I think Kawasaki set all their gauges very conservative to help protect the riders, such as the speedometer reading 5% high, fuel showing empty when there is 1/2 a tank left, etc. When I had my 900 I bent the float rod down just a bit and the guage was almost dead accurate.
 

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Since we're the human component of this bike/rider combination, we have the ability to adapt and adjust. To paraphrase the famous Marine prayer: "This is my Vulcan. There are many like it but this one is mine." (Insert your own bike in there.)

I know what mine is like and how much to directly trust its range and closely approximate its' mpg. I know just how the fuel gauge is off, as far as accuracy, and how the mpg varies (greatly) according to my sustained speed. I know where the rpm threshold is when I'm no longer running just off the pilot jets but when the mains kick in, or shut off as the case may be.

Basically, I have enough instruments to get along fine. I'd like a more modern sensor suite, sure, but not so much if it would just be adding more stuff to guess about. I'd REALLY like to have a stand-alone on-board navigation system but my Garmin fills that square quite nicely, so essentially, I'm ok.

As a matter of course, each of us simply gets used to what we have in front of us. Its a shame though that they're not across the board precise. I think its a wonder that someone, somewhere hasn't sued the living hell out of a manufacturer for the built-in inaccuracies. It'll happen. Someone will get caught out of gas somewhere because of a "miles to empty" gauge being off. Although I also think T Gibbs is correct when he essentially alluded to the fudge factor tends to go in the rider's favor so a lawsuit might be difficult to win.

Still, I'd prefer for there to be no fudge factor. I'd rather have accurate instruments.
 

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As far as gas pump accuracy goes I think they have to be calibrated but I've not a clue as to how often. Even with the pen/paper/calculator method you can only be as accurate as your inaccurate speedo/odometer allows you to be.

As for the increased resistance from the alternator, I still don't see how that matters at all in regards to MPG. Unless you run a TON of electrical doo-dads that pulls juice from the spark plugs how can it affect MPG much less be in the same universe as trying to determine MPG? Or is this an ECU-thing where if it gets too little juice to its brain it goes all weird in engine timing etc. etc.? (I'm happy that mine doesn't have an ECU.)

Apparently, there is some basic working theory and mathematical equation the ECU uses that I'm not grasping. When I figure MPG I take the amount of physical gasoline I filled up with and that figure is divided into the number of miles I've ridden (which will be off by perhaps 5% or so). This divided by that equals MPG. Its a pretty simple equation. What would any possible equation using current flow as a replacement for distance driven and/or fuel used even look like?

Current flow should mean squat. Which seems to be the case since everyone gripes about their bike being so wrong in the results it displays.
I did say "if you have accessories that draw significant power". If the mpg is based on stock electronics and you add some high amp spots, ride on a cold day with a full set of heated liners and gloves, etc., you will be drawing significantly more amps than the stock bike will draw. Some folks add some pretty hefty amplifiers and radios to their bikes. These can can add up, which is also why some folks damage their charging systems or kill their batteries. They add more accessories than the bike can handle.

The ECU has no way off accommodating those extra amps. Is it enough to effect the calculated mpg? Maybe not until it is added to all of the other things that can effect the actual vs. calculated mileage.
 

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Sabre-T you added your last two posts while I was typing my last one. So the bike uses the float as the method of determining gas usage??? I don't doubt your statement at all but that seems to be a built-in problem right from jump street. If I had to depend on the accuracy of the fuel tank float or the accuracy of a gas pump at a station, I'll always go with the gas pump, hands down.

How does the speedo work on ECU bikes? Is it some electrical thing, too? Mine is driven by the front wheel RPMs so its a physical input.

LOL, this conversation is making me less and less trust newer bikes.
As far as I know, all vehicles with fuel gauges use some sort of float to measure the amount of gas in the tank. Yes, the gas pump is probably much more accurate in most places than your fuel gauge. I guess it depends on each states laws and how closely the vendors in the various states are monitored. I think most states have pretty strict laws and monitor the vendors pretty closely these days.

Without being an electrical engineer or a bike mechanic i will just use common sense. I have owned cars with the estimated miles to empty and a running miles per gallon and they never ever jump around as some have stated and as for motorcycles i rented the Indian Roadmaster and put a little over 1000 miles on it and it also never ever jumped around and i can assume other manufactures have also figured out how to make this work. The float jumping around just seams like 1960 technology and the electrical draw is a non starter the bike puts out plenty of juice to handle add on's not to mention its own on board systems. I like my voyager and I'll keep it but lets just admit it Kawasaki installed a very low quality system and had 10 years to fix it.
Some floats have dampeners on them to slow down the rise and fall so you don't get the wild changes that you see in other vehicles. The shape of the tank and the position of the sensor in the tank also have an effect. However, even when dampened, you can see huge swings. Going up one side of a mountain, the distance to empty will usually be quite a bit less than when going down the other side. In my wife's car, we have seen it go from something like 75 - 100 miles to empty going up a steep mountain to 500+ miles to empty coming down the other side.

The capacity to produce the extra power does not mean it won't use gas to produce that extra power. And I'll say it again, the electrical draw is just one of a number of things that affect the mpg estimations. So do the riders/passengers/cargo weights, the road conditions, and wind. These are accounted for by the throttle position sensor, but how accurate is that for determining the volume of gas used? It all adds up to throw off the calculations. These are things that the ECU cannot take into account when doing it's calculations.
 
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