Author Topic: '12 speedometer accuracy?  (Read 4074 times)

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Offline luv2fly

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'12 speedometer accuracy?
« on: May 17, 2014, 11:15:31 pm »
I'm just under 700 miles on my '12.  So, everything is brand new.  For you guys that have a GPS, how accurate are our speedos? Going down the interstate in my car I usually run 75'ish'.  On my C14, I've run 80 and still get passed occasionally.   At an indicated 75 it seems I'm not keeping up with traffic.  Not the case at those indicated speeds in my car.  So is my bike speedo that far off?  My 85 V65 was 3% optimistic against a GPS I had on that.

On a lighter note I caught myself at an indicated 95 today.  I was shocked as it felt like a solid 60 MPH.  Rolled off and checked my 6! :-\
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Offline instructor

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Re: '12 speedometer accuracy?
« Reply #1 on: May 17, 2014, 11:40:10 pm »
Might not be a super accurate way to check the speedometer, but coming up on construction project on Interstate and noticed the speed indicator showing 70mph and glanced at the speedometer and sure enough, reading 70mph. Backed off to just slightly over 55mph and several cars went right by me still going 70mph plus. Apparently they can't read or just don't give a hoot about what the speed indicator reads. They will care if they get a ticket in these areas for believe it is twice the normal speeding fine. I would prefer to spend that kind of money on a set of new tires rather than give it to the State. 

Offline fartymarty

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Re: '12 speedometer accuracy?
« Reply #2 on: May 18, 2014, 01:56:16 am »
I'm fairly certain that the speedos are optimistic by about 3-4 mph in the 80mph area of the gauge. That's with
a 190/50 tire on the rear. I'm told by others that a 190/55 rear makes the speedo almost dead on the money with the GPS.


Offline CW

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Re: '12 speedometer accuracy?
« Reply #3 on: May 18, 2014, 01:39:29 pm »
With OEM-sized tires, speedo errors of 7-10% overstatement are fairly common on Japanese vehicles. At least that has been my experience with a Honda VTX, a Hayabusa, a KLR, my C14, and two different Honda Accords.

Maybe not so coincidentally, Honda North America settled a threatened class action several years ago by extending the original factory warranty due to overstated odometer readings in the Accords and Civics.

The consensus nowadays, at least for bikes, is that while speedos may continue to be overstated, distances (the odos) are more accurate. I do not understand the technology that would allow distance to be accurate while overstating speed...unless there are two independent measuring systems.
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Offline Alekkas

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Re: '12 speedometer accuracy?
« Reply #4 on: May 18, 2014, 06:36:54 pm »
While getting radared (with the sign preferably, not a ticket!) helps, one ride with a gps or a pillion holding a gps, settles the matter.

Don't forget to get various speeds like 30, 50, 70, 80, etc...  I always considered this a % matter, but on my vulcan, it wasn't a consistent % from one end of the speedo to the other.  Go figure.
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Offline mattchewn

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Re: '12 speedometer accuracy?
« Reply #5 on: May 18, 2014, 07:56:10 pm »
luv2fly,
My speedo on stock tires was 4.5 mph on the faster than actual side. With my first 55 series rear tire ( first run Angel GT) it zeroed out perfectly for the first 3k or so of tire wear. My second Angel GT (also a 55 series) the speedo is off 1 MPH at 80 indicated. I guess the tire molds are slightly different after all. With my GPS vs odometer at the end of a 328 mile ride the odometer was off from the GPS only .6 miles. I think I can live with that. My odometer is off like .2%
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Offline Bur

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Re: '12 speedometer accuracy?
« Reply #6 on: May 18, 2014, 11:52:23 pm »
With OEM-sized tires, speedo errors of 7-10% overstatement are fairly common on Japanese vehicles. At least that has been my experience with a Honda VTX, a Hayabusa, a KLR, my C14, and two different Honda Accords.

Maybe not so coincidentally, Honda North America settled a threatened class action several years ago by extending the original factory warranty due to overstated odometer readings in the Accords and Civics.

The consensus nowadays, at least for bikes, is that while speedos may continue to be overstated, distances (the odos) are more accurate. I do not understand the technology that would allow distance to be accurate while overstating speed...unless there are two independent measuring systems.

As a C10 owner, I was preparing to say something snarky, like "Just ask the officer, he'll even give you written proof of how fast you were going to compare", but then I read this comment, and agree-Miss Swail seems to have an "optimistic" speedometer but was dead on the distance on Google Maps directions today via the odometer.  PFM?
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Offline WillyP

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Re: '12 speedometer accuracy?
« Reply #7 on: May 19, 2014, 12:16:18 am »
The two measurements aren't directly related. In a mechanical speedometer, the odometer simply is geared from the front wheel. the odometer turns x revolutions for every n revolution of the front wheel. The speedometer, on the other hand, measures how fast the wheel is turning. Essentially the front wheel drives what amounts to (in layman's terms) a tiny generator, and the speedometer measures the output from that. Generaly speedometers are designed to indicate a higher than actual speed because the manufacturers don't want to get sued for a speedometer reading a slower speed. And there is a certain tolerance for the calibration. So they would want to err on the side of reading high. Police cars have more accurately calibrated speedometers.
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Offline TimR

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Re: '12 speedometer accuracy?
« Reply #8 on: May 19, 2014, 12:36:37 am »
Quote
Police cars have more accurately calibrated speedometers.

Maybe. I driven some police cars with "calibrated" speedos that were off by 3 or 4 MPH.
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Offline stevewfl

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Re: '12 speedometer accuracy?
« Reply #9 on: May 19, 2014, 01:35:31 am »
google is your friend. You'll soon figure out none of the indicators on this bike are "accurate". However, the temp gauge is closer to accurate than the weatherman
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Offline firehawk618

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Re: '12 speedometer accuracy?
« Reply #10 on: May 19, 2014, 05:25:28 am »
Mine seems to be pretty damned accurate.  Off maybe 2-3 mph at 70.

Problem is that it's so hard to go 70, the bike wants to go 90.......bad bad bad
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Offline CW

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Re: '12 speedometer accuracy?
« Reply #11 on: May 19, 2014, 11:09:41 am »
The two measurements aren't directly related. In a mechanical speedometer, the odometer simply is geared from the front wheel. the odometer turns x revolutions for every n revolution of the front wheel. The speedometer, on the other hand, measures how fast the wheel is turning. Essentially the front wheel drives what amounts to (in layman's terms) a tiny generator, and the speedometer measures the output from that. Generaly speedometers are designed to indicate a higher than actual speed because the manufacturers don't want to get sued for a speedometer reading a slower speed. And there is a certain tolerance for the calibration. So they would want to err on the side of reading high. Police cars have more accurately calibrated speedometers.

Don't remember seeing anything geared from the front wheel of my C14...or my Busa, or VTX for that matter...have to look again when I get the chance.
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Offline Grumpy Goat

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Re: '12 speedometer accuracy?
« Reply #12 on: May 19, 2014, 11:18:36 am »
I'm told by others that a 190/55 rear makes the speedo almost dead on the money with the GPS.

Yup, I can confirm that. Accurate to within less than the thickness of the needle.
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Re: '12 speedometer accuracy?
« Reply #13 on: May 19, 2014, 11:51:53 am »
The two measurements aren't directly related. In a mechanical speedometer, the odometer simply is geared from the front wheel. the odometer turns x revolutions for every n revolution of the front wheel. The speedometer, on the other hand, measures how fast the wheel is turning. Essentially the front wheel drives what amounts to (in layman's terms) a tiny generator, and the speedometer measures the output from that. Generaly speedometers are designed to indicate a higher than actual speed because the manufacturers don't want to get sued for a speedometer reading a slower speed. And there is a certain tolerance for the calibration. So they would want to err on the side of reading high. Police cars have more accurately calibrated speedometers.

Don't remember seeing anything geared from the front wheel of my C14...or my Busa, or VTX for that matter...have to look again when I get the chance.

The C14 has a speed sensor that picks up a signal on the output shaft of the transmission.
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Offline WillyP

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Re: '12 speedometer accuracy?
« Reply #14 on: May 19, 2014, 01:37:08 pm »
Doesn't matter, that is just a sending unit that sends a signal to the speedometer. If the C-14 has a digital odometer, it simply counts revolutions, and calculates mileage. If it had a digital speedometer, it would take that count and apply a time factor to get miles per hour. If it has an analog speedometer, it would then convert the result of that to an analog voltage, and send that signal to a meter movement.

The point is, that calibration of one readout does not necessarily affect the other.
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Offline firehawk618

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Re: '12 speedometer accuracy?
« Reply #15 on: May 19, 2014, 05:53:53 pm »
Doesn't matter, that is just a sending unit that sends a signal to the speedometer. If the C-14 has a digital odometer, it simply counts revolutions, and calculates mileage. If it had a digital speedometer, it would take that count and apply a time factor to get miles per hour. If it has an analog speedometer, it would then convert the result of that to an analog voltage, and send that signal to a meter movement.

The point is, that calibration of one readout does not necessarily affect the other.

Exactly right.  Mechanical or digital this all applies.

One example jumps to mind.  MK IV Golf TDI I used to have.  The MPH read high at highway speeds but the odometer always matched up perfectly with mile markers.  I plugged in Vag-Com and pulled up the vehicle speed.  The speed in Vag-Com was exactly right but the displayed speed was not.  That proved to me they intentionally show a slightly high displayed speed.

On that car I was able to edit the bin dump of that cluster and re-flashed the edited bin to correct the speedometer BUT it cost me odometer accuracy unfortunately.  After that the speedometer was right but odometer was slightly low.
« Last Edit: May 19, 2014, 05:57:06 pm by firehawk618 »
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Offline Bruiser

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Re: '12 speedometer accuracy?
« Reply #16 on: May 19, 2014, 07:49:24 pm »
Maybe its just me, but if Im doing 70 and cars pass me, its just that....they are going faster than me.  :34:
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Offline Fred_Wa2gzw

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Re: '12 speedometer accuracy?
« Reply #17 on: May 20, 2014, 11:46:10 pm »
On my 12 at speedometer indicated 64 mph my GPS indicates I am doing 60.   My back tire is the Kawi specified 50 series tire(Michelin PR3).

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Offline LakeTrax

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Re: '12 speedometer accuracy?
« Reply #18 on: May 21, 2014, 02:47:31 am »
As all have already said, my 2012 speedo was slightly optimistic from the factory.(as most all vehicles I've ever had)
Installed a PR2 190/55 and it's been close-enough to accurate for me since.
Never have tracked actual mileage vs. odometer readings though-
More on that later-

I hadn't been in years..
but I got dinged a couple weekends ago.
89 in a 55- :-\
KSP's "moving LASAR" doesn't discriminate I suppose...
It will only hurt a little they say... Right? :(

I'm just glad he didn't catch me 200 glorious miles earlier that Sunday afternoon doing something truly "jail 'n tow" worthy. :nananana:

Here's to hoping the judge likes me next month... :beerchug:

What I don't get about the speedo/odo thing is this and this:
Doesn't matter, that is just a sending unit that sends a signal to the speedometer. If the C-14 has a digital odometer, it simply counts revolutions, and calculates mileage. If it had a digital speedometer, it would take that count and apply a time factor to get miles per hour. If it has an analog speedometer, it would then convert the result of that to an analog voltage, and send that signal to a meter movement.

The point is, that calibration of one readout does not necessarily affect the other.

Exactly right.  Mechanical or digital this all applies.

One example jumps to mind.  MK IV Golf TDI I used to have.  The MPH read high at highway speeds but the odometer always matched up perfectly with mile markers.  I plugged in Vag-Com and pulled up the vehicle speed.  The speed in Vag-Com was exactly right but the displayed speed was not.  That proved to me they intentionally show a slightly high displayed speed.

On that car I was able to edit the bin dump of that cluster and re-flashed the edited bin to correct the speedometer BUT it cost me odometer accuracy unfortunately.  After that the speedometer was right but odometer was slightly low.

No, calibration doesn't matter... if you're the programmer or engineer.

But whether it's digital or analog, doesn't the ratio between speedo error & odometer error remain constant?
If one changes, won't the other also in direct proportion? :017:
« Last Edit: May 21, 2014, 02:57:38 am by LakeTrax »

Offline firehawk618

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Re: '12 speedometer accuracy?
« Reply #19 on: May 21, 2014, 05:12:07 am »
As all have already said, my 2012 speedo was slightly optimistic from the factory.(as most all vehicles I've ever had)
Installed a PR2 190/55 and it's been close-enough to accurate for me since.
Never have tracked actual mileage vs. odometer readings though-
More on that later-

I hadn't been in years..
but I got dinged a couple weekends ago.
89 in a 55- :-\
KSP's "moving LASAR" doesn't discriminate I suppose...
It will only hurt a little they say... Right? :(

I'm just glad he didn't catch me 200 glorious miles earlier that Sunday afternoon doing something truly "jail 'n tow" worthy. :nananana:

Here's to hoping the judge likes me next month... :beerchug:

What I don't get about the speedo/odo thing is this and this:
Doesn't matter, that is just a sending unit that sends a signal to the speedometer. If the C-14 has a digital odometer, it simply counts revolutions, and calculates mileage. If it had a digital speedometer, it would take that count and apply a time factor to get miles per hour. If it has an analog speedometer, it would then convert the result of that to an analog voltage, and send that signal to a meter movement.

The point is, that calibration of one readout does not necessarily affect the other.

Exactly right.  Mechanical or digital this all applies.

One example jumps to mind.  MK IV Golf TDI I used to have.  The MPH read high at highway speeds but the odometer always matched up perfectly with mile markers.  I plugged in Vag-Com and pulled up the vehicle speed.  The speed in Vag-Com was exactly right but the displayed speed was not.  That proved to me they intentionally show a slightly high displayed speed.

On that car I was able to edit the bin dump of that cluster and re-flashed the edited bin to correct the speedometer BUT it cost me odometer accuracy unfortunately.  After that the speedometer was right but odometer was slightly low.

No, calibration doesn't matter... if you're the programmer or engineer.

But whether it's digital or analog, doesn't the ratio between speedo error & odometer error remain constant?
If one changes, won't the other also in direct proportion? :017:

The thing is on the example I stated.   By default the odo was accurate, speedo was high.  When I messed with the hex dump from the cluster and corrected the speedo, the odo was now low.  So the correlation of the two was somewhere in the cluster that I couldn't access or simply didn't know how to. 

But the 2 in that car were most definitely changed together by the one hex character I changed in the bin file.
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Offline LakeTrax

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Re: '12 speedometer accuracy?
« Reply #20 on: May 21, 2014, 02:28:14 pm »
I understand that one or the other's calibration can be 100% accurate while the other one is a certain percentage off...
This is done by whoever is in charge of design from the factory-
They can also set the calibrations/relationship between the speedo and odometer to whatever they want.
One(or both) high, low, accurate, etc...
.
All I was trying to say was that once the calibrations are set,
If you alter one of them(with different tire sizes, reflashing, whatever)...
The other one will then be altered as well. In direct proportion-

Thus, the calibration of one readout DOES affect the other.

Offline Daytona_Mike

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Re: '12 speedometer accuracy?
« Reply #21 on: May 21, 2014, 03:20:25 pm »
I know that 170mph indicated is really 162mph on my gps and that was with a 55 series. I am back on a 50 and I would think it is now off by more due to the smaller diameter..
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Offline C14lvr

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Re: '12 speedometer accuracy?
« Reply #22 on: May 23, 2014, 01:31:28 am »
I know that 170mph indicated is really 162mph on my gps and that was with a 55 series. I am back on a 50 and I would think it is now off by more due to the smaller diameter..


Now how would you know 170 is really 162... Huh??
Have you been a naughty boy?

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Then,  just as drool began to form on my bottom lip, and my mind began to list all the reasons why I should buy it, an angel appeared on my right shoulder and said, "Don't do it, Bobby... You know you'll have to prove it really will go 202 mph..."
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Offline LakeTrax

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Re: '12 speedometer accuracy?
« Reply #23 on: May 23, 2014, 02:48:09 am »
^^^^^
That's why I'm so mad at myself about getting the recent ticket.
I've seen both angels... on both shoulders!

I bought a brand new '09 ZX14 in Oct.'08-
Told my boss at the time(also dealership owner)that I was 30... not 40.
Said I wasn't ready to go for the C14 and all of it's hard-bagged endless-farkle glory just yet.
I also didn't like the C14's factory-offered color/s at the time-
SilverDammit!!! :))

Had the ZX14 for over 2 years... 20k+ miles and no tickets of any kind. :beerchug:

Here I am 6 years later...
Married(w/ step-kids), salt 'n pepper hair-do justa kickin', fully licensed, insured, and geared up...
And I get popped for 34mph over on a "grandpa's bike"? :-[

Ahhh... such is life. :truce:
« Last Edit: May 23, 2014, 02:51:52 am by LakeTrax »

Offline WillyP

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Re: '12 speedometer accuracy?
« Reply #24 on: May 23, 2014, 06:29:36 pm »
I understand that one or the other's calibration can be 100% accurate while the other one is a certain percentage off...
This is done by whoever is in charge of design from the factory-
They can also set the calibrations/relationship between the speedo and odometer to whatever they want.
One(or both) high, low, accurate, etc...
.
All I was trying to say was that once the calibrations are set,
If you alter one of them(with different tire sizes, reflashing, whatever)...
The other one will then be altered as well. In direct proportion-

Thus, the calibration of one readout DOES affect the other.

In that case you are right, but the original comment that started this was:

With OEM-sized tires, speedo errors of 7-10% overstatement are fairly common on Japanese vehicles. At least that has been my experience with a Honda VTX, a Hayabusa, a KLR, my C14, and two different Honda Accords.

Maybe not so coincidentally, Honda North America settled a threatened class action several years ago by extending the original factory warranty due to overstated odometer readings in the Accords and Civics.

The consensus nowadays, at least for bikes, is that while speedos may continue to be overstated, distances (the odos) are more accurate. I do not understand the technology that would allow distance to be accurate while overstating speed...unless there are two independent measuring systems.

Manufacturers, as far as I know, have always calibrated speedometers to overstate speed.
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