Re: Speedo error

[Art Borin <ArtBorin@frontiernet.net>]

Sean E. Mulch wrote:

> I set my cruise at an indicated 70 mph last night. I then reset my
> computer and watched the average MPH for a few miles. It read 66 mph.
> Now what is this telling us?
> That our analog speedos are incorrect! They read on the high side!If
> this is a percentage error, the inaccuracy will increase with speed.

It's probably not a percentage error.  On my BMW motorcycle, the factory
built in a 3 mph error on the high side.  I know because I mounted a
bicycle computer to the beast and logged the difference at 20 thru 70 at
10 mph increments.  At all speeds, the speedo reads 3 mph high.  Almost
everyone else on the beemer list that rides a R1100RS has a similar
error.

If accurate analog readings are important to you, get your speedo
calibrated.  If you can't find a local shop, there are a few places that
do it by mail order.

Overseas speedo - 800-444-0292

Palo Alto Speedometer - 650-323-0243


> So all you 140+ top speeders are probably being duped by you incorrect
> speedos. All published documentation I've seen indicates that our top
> speed is around 128mph.

Yup.  Ignorance is bliss!

>
>
> Just so nobody screams at me about worn out tires causeing the
> problem. I've only 6600 miles on my baby!

Good point.  This would cause a percentage error, but probably only
about 2%.  Your speedo error is more like 6%.  We can guess that the
factory has an error tolerance spec. for the speedo, maybe +/- 5%, at an
average tire wear point.  If your speedo is out of spec, maybe +10%, 128
would indicate 141, not factoring in tire growth at speed.  A good
theory, for sure.

>
>
> Sean Mulch
> 98 GLX Red/Blk
> Stock.
>



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Art Borin, Jr.
AMSCO Wear Products Inc.
P.O. Box 269
289 West Main Street
Goshen, NY  10924
Phone: (914) 294-1805
Fax: (914) 294-1657

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