Author Topic: Speedometer Calibration  (Read 11160 times)

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Offline burmashave

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Re: Speedometer Calibration
« Reply #25 on: September 15, 2006, 05:01:22 PM »

And in reality, how often does, say, a warranty situation happen just as a vehicle is about to leave warranty....??


I was joking, but only slightly.  A class action would not be out of the question in the US.  (See overlawyered.com for examples.)  On the other hand, I don't think SOHC/4 owners could present themselves as injured parties.

I'm guessing things might be different up your way. BTW, I passed through Kamloops some time back, and I think it has the coolest name for a city with a close second going to Medicine Hat. ;D
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Offline Loudpipe

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Re: Speedometer Calibration
« Reply #26 on: September 15, 2006, 07:19:54 PM »
You know, if they just calibrated them right from the factory, this discussion wouldn't even be necessary, let alone a lawsuit.  ;D
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Previous: 1978 Honda CB750F, 1971 Honda CB500K, 2009 Yamaha YZF-R1

Offline nickjtc

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Re: Speedometer Calibration
« Reply #27 on: September 15, 2006, 09:38:15 PM »
I passed through Kamloops some time back, and I think it has the coolest name for a city with a close second going to Medicine Hat. ;D

Kamloops: from the native Koom clops, meaning 'meeting of the the waters'.
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Offline nickjtc

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Re: Speedometer Calibration
« Reply #28 on: September 15, 2006, 09:40:32 PM »
You know, if they just calibrated them right from the factory, this discussion wouldn't even be necessary, let alone a lawsuit.  ;D

Ah yes, but the factory would calibrate it just right, and then a bunch of sohc owners would want to put different sized tyres on their bikes and mess it all up again!
Nick J. Member #3247

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Offline MikeDeB

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Re: Speedometer Calibration
« Reply #29 on: September 16, 2006, 06:34:26 AM »
And if your odometer reads high, you're actually getting worse gas mileage than your'd be figuring.

But that's just it.  The odometer should be fairly accurate (with a fresh front tire of correct size).  It is directly driven off the cable drive.  The speedo needle is magnetically driven.
Mike (Old SOHC/4 #2641)
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Offline MikeDeB

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Re: Speedometer Calibration
« Reply #30 on: September 16, 2006, 07:05:08 AM »
It can be calibrated to a specific speed. Heres a PDF file that explains it on Smiths speedos. The CB speedos use the same principals as the Smiths'

    Look for SPEEDOMETER calibration, about at the middle of the file.

http://mywebpages.comcast.net/rhodes/speedo.pdf#search=%22recalibrating%20speedometers%22

Daniel



Excellent article.  I've saved it for future use.   ;D
Mike (Old SOHC/4 #2641)
Holt, MI
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Offline burmashave

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Re: Speedometer Calibration
« Reply #31 on: September 16, 2006, 08:37:25 AM »
Excellent article.  I've saved it for future use.   ;D
Me too.  ;D
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Offline nickjtc

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Re: Speedometer Calibration
« Reply #32 on: September 16, 2006, 11:10:40 AM »
And if your odometer reads high, you're actually getting worse gas mileage than your'd be figuring.

But that's just it.  The odometer should be fairly accurate (with a fresh front tire of correct size).  It is directly driven off the cable drive.  The speedo needle is magnetically driven.

But only if the OEM calibrates the speedo exactly for the 'stock' size tyre, with no bias. As we have found out, they do fiddle with the calibtration, deliberately, so that the instrument is optimistic.
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Offline Gordon

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Re: Speedometer Calibration
« Reply #33 on: September 16, 2006, 11:18:37 AM »
And if your odometer reads high, you're actually getting worse gas mileage than your'd be figuring.

But that's just it.  The odometer should be fairly accurate (with a fresh front tire of correct size).  It is directly driven off the cable drive.  The speedo needle is magnetically driven.

But only if the OEM calibrates the speedo exactly for the 'stock' size tyre, with no bias. As we have found out, they do fiddle with the calibtration, deliberately, so that the instrument is optimistic.

He's talking about the odometer, you're talking about the speedometer.  Two completely different systems as far as calibration goes.  It's possible for the odometer to be giving a near exact measurement of distance at the same time that the speedo is reading 20% off of actual speed. 

Offline nickjtc

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Re: Speedometer Calibration
« Reply #34 on: September 16, 2006, 11:30:44 AM »
He's talking about the odometer, you're talking about the speedometer.  Two completely different systems as far as calibration goes.  It's possible for the odometer to be giving a near exact measurement of distance at the same time that the speedo is reading 20% off of actual speed. 

You're absolutely right. So there must be some reason why the OEM's link the 'inaccuracies' together...
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Offline Gordon

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Re: Speedometer Calibration
« Reply #35 on: September 16, 2006, 11:43:36 AM »
Probably just to cover their own asses.

I haven't tested the guages on my current bikes, but on the 400F I had back in Texas, the odometer was almost dead on, while the speedometer registered about 8% over actual speed. 

Offline MikeDeB

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Re: Speedometer Calibration
« Reply #36 on: September 16, 2006, 12:16:53 PM »
Probably just to cover their own asses.

I haven't tested the guages on my current bikes, but on the 400F I had back in Texas, the odometer was almost dead on, while the speedometer registered about 8% over actual speed. 

I'm getting about the same with both Ducs.
Mike (Old SOHC/4 #2641)
Holt, MI
71 CB750K1
72 CB750K2
72 CB100K2
97 Ducati 900 SS/SP w/FCRs
98 Ducati 750 Monster w/FCRs
80 SR500

"Growing older is inevitable, growing up is an option."