SuzukiSavage.com - Speedometer Accuracey

Cavie Full Member Offline My wife made me do it Posts: 107 Port charlotte Fl Gender:	Speedometer Accuracey 03/18/12 at 19:46:45 I know the speedometer on my Volusia is 5 MPH slow. They all are 5-8 mph off. How about the S-40. Are they accurate?
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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: Speedometer Accuracey Reply #1 - 03/18/12 at 19:52:35 about the same till you put a 140/90-15 on, then it's about right.
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ralfyguy Serious Thumper Offline Posts: 932	Re: Speedometer Accuracey Reply #2 - 03/18/12 at 21:10:03 Mine shows about the same speed as my GPS phone app with stock tire size.
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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: Speedometer Accuracey Reply #3 - 03/18/12 at 22:38:16 I know the speedometer on my Volusia is 5 MPH slow. Shows -5 at a stop? 5 mph at 10? 65 WHEN RUNNIN 70? 95 when runnin 100?
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Re: Speedometer Accuracey
Reply #4 - 03/19/12 at 06:22:06

verslagen1 wrote on 03/18/12 at 19:52:35:

about the same till you put a 140/90-15 on, then it's about right.

+1
This has been discussed a lot on BurgmanUSA.com. The Suzuki Burgman 650 speedometer reads 9-10% faster than actual speed. Most vehicles will read faster than actual speed. Speedometers can read up to 10% faster than actual speed but not slower.

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: Speedometer Accuracey Reply #5 - 03/19/12 at 07:14:32 It's typical of all vehicle mfr's. The last thing they want is for a customer to sue them for a number of speeding tickets and a documented incorrect speedo.
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Cavie Full Member Offline My wife made me do it Posts: 107 Port charlotte Fl Gender:	Re: Speedometer Accuracey Reply #6 - 03/19/12 at 09:21:08 justin_o_guy2 wrote on 03/18/12 at 22:38:16: I know the speedometer on my Volusia is 5 MPH slow. Shows -5 at a stop? 5 mph at 10? 65 WHEN RUNNIN 70? 95 when runnin 100? Vol shows 5-7 mph faster at all speeds using roads side (Your speed) radar signs. Sits at 0.
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Serowbot

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OK.... so what's the
speed of dark?

Posts: 28644
Tucson Az
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Re: Speedometer Accuracey
Reply #7 - 03/19/12 at 09:48:12

FYI... from the department of odd facts...

Speedometers aren't actually gear driven, as many people believe...
The needle indicator is not physically attached to speedo cable at all..
It's position is varied by an electromagnetic force called an eddy current...
The end of the speedo cable rotates a magnet within a thingy called a speedcup that the needle is attached to, and as the magnetic field increases, the needle moves...

Oh,.. the weirdness!...

No, don't thank me... I'm just a fount of useless information... Grin

...

Why did I post this?... Because I have no other useful reason for storing such a stupid little factiod...
Huh

...

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Ludicrous Speed !... ... Huh

...

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spacepirates

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Re: Speedometer Accuracey
Reply #8 - 03/19/12 at 11:17:43

Serowbot wrote on 03/19/12 at 09:48:12:

FYI... from the department of odd facts...

Speedometers aren't actually gear driven, as many people believe...
The needle indicator is not physically attached to speedo cable at all..
It's position is varied by an electromagnetic force called an eddy current...
The end of the speedo cable rotates a magnet within a thingy called a speedcup that the needle is attached to, and as the magnetic field increases, the needle moves...

Oh,.. the weirdness!...

No, don't thank me... I'm just a fount of useless information... Grin

...

Why did I post this?... Because I have no other useful reason for storing such a stupid little factiod...
Huh

...

This interested me, so I looked it up: http://en.wikipedia.org/wiki/Speedometer#Eddy_current

Seems like post 1980's they switched to electronic operation, though the fact still stands that there isn't a physical-drive connection in either method. neat-o.

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Boofer Serious Thumper Offline Nearly too old. Posts: 1760 N Ms Gender:	Re: Speedometer Accuracey Reply #9 - 03/20/12 at 14:22:34 Serow, A day on Mars is 24 hours, 35 minutes, 22.7 seconds, I think. I learned that in school and can't forget it. Now I'm just goofy, but you is uncommon smart.
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Savage_Rob

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Re: Speedometer Accuracey
Reply #10 - 03/20/12 at 14:28:13

spacepirates wrote on 03/19/12 at 11:17:43:

Serowbot wrote on 03/19/12 at 09:48:12:

FYI... from the department of odd facts...

Speedometers aren't actually gear driven, as many people believe...
The needle indicator is not physically attached to speedo cable at all..
It's position is varied by an electromagnetic force called an eddy current...
The end of the speedo cable rotates a magnet within a thingy called a speedcup that the needle is attached to, and as the magnetic field increases, the needle moves...

Oh,.. the weirdness!...

No, don't thank me... I'm just a fount of useless information... Grin

...

Why did I post this?... Because I have no other useful reason for storing such a stupid little factiod...
Huh

...

This interested me, so I looked it up: http://en.wikipedia.org/wiki/Speedometer#Eddy_current

Seems like post 1980's they switched to electronic operation, though the fact still stands that there isn't a physical-drive connection in either method. neat-o.

If the rest of the world just switched to electronics in the 80's, our thumpers are likely still using magnets. They would be cheap since nobody else wanted them anymore. I like less electronics anyway, so I hope they use magnets.

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Serowbot

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OK.... so what's the
speed of dark?

Posts: 28644
Tucson Az
Gender: male

Re: Speedometer Accuracey
Reply #11 - 03/20/12 at 16:27:07

Savage_Rob wrote on 03/20/12 at 14:28:13:

If the rest of the world just switched to electronics in the 80's, our thumpers are likely still using magnets. They would be cheap since nobody else wanted them anymore. I like less electronics anyway, so I hope they use magnets.

I think,.. by "electric",.. they are referring to digtal LCD type speedo's...
Most cars and some bikes have them,... we don't...
Our's is old fashioned eddy current manual...
Wink

...

Boofer wrote on 03/20/12 at 14:22:34:

Serow, A day on Mars is 24 hours, 35 minutes, 22.7 seconds, ...

No wonder the Martians are so far ahead of us... Huh

...

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« Last Edit: 03/20/12 at 18:09:05 by Serowbot »

Ludicrous Speed !... ... Huh

...

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J C Stokes Full Member Offline SuzukiSavage.com Rocks! Posts: 159	Re: Speedometer Accuracey Reply #12 - 06/07/12 at 03:54:46 Hmm, I just put a 140/90 15 on. Nice to know the speedo should be accurate.
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Re: Speedometer Accuracey
Reply #13 - 06/07/12 at 07:58:58

verslagen1 wrote on 03/19/12 at 07:14:32:

It's typical of all vehicle mfr's.
The last thing they want is for a customer to sue them for a number of speeding tickets and a documented incorrect speedo.

If this is the case, wouldn't the mfrs want to the speedo to read too fast, instead of too slow? A speedo that reads too slow will GET you tickets (i.e., you think you're going 65, but really doing 70). Also if your speedo reads too slow (compared to real speed), then going to a larger aspect ratio tire will make it even slower, because the tire RPM will be lower for any given real speed.

The speedo reading is directly proportional to tire RPM, but varies with tire diameter when compared to real speed. In other words, the overall final ratio will change with the tire size/mfr and also as the tire wears out (it rotates faster, or more times for a given distance). It is pretty easy to calculate the theoretical speedo reading based on various tire diameters. In another thread think I calculated 4 to 5% decrease in tire RPM going from an 80 to a 90 aspect ratio tire (assuming 140 width). By the same token you can measure tread depth when the tire is new and figure out how much smaller the tire will become as it wears out. This will give you a speedo reading delta: new vs worn out.

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sjaskow - FSO Senior Member Offline Posts: 365 Frozen Tundra of MN Gender:	Re: Speedometer Accuracey Reply #14 - 06/07/12 at 09:57:14 I have a 140/90-15 D404 on the back of my 06. The speedometer now seems to be accurate but my odometer is now 1/10 of a mile short per mile. This means for every actual mile I drive, I only record 9/10 of one.
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