Speedo question. Not the swimsuit

[cbelawn]

I bought a 1993 K 1100 RS last year the speed of a would cut out periodically. So after reading some post I took the speedometer apart clean the 3 connectors and put it back together. According to my GPS the speedometer runs faster than what the GPS says. Going down the road at 55 the speedometer shows 70. I would appreciate any thoughts on this

[johnny]

greetings...

your gps is not reliable because brick speedos are 100% accurate... especially on the eleven hundert reise strasse...

use the tach... 8,000 rpm is 70mph in 4th gear...

j o

[rbm]

First, validate one of your devices as accurate so that you can use it as a reference.  Otherwise, it's going to be like the old adage that "a man with two watches never knows the time".

Operate your GPS in a car which has an odometer you "trust", driving at various set speeds to see if the GPS corresponds.  If it does, then assume that it is your reference.

Run the motorcycle at the set speed suggested by Johnny, or use the Excel calculator to get a range of speed marks.  Then run your bike at those speed marks to determine if the speedometer is out of calibration or not.

Once you have your reference, make a determination as to whether the speedometer is registering fast or slow.  Then use the potentiometer inside the cluster to adjust the speedometer driver.

[natalena]

If you want to avoid taking the cluster apart, there's a unique solution that is very accurate to determine speed.

Locate a school zone with a digital speed readout camera.
Motor through at the last known "GPS guessed" speed, in this case 70mph. (3 times is good for an average)
A light will flash in a stutter fashion, confirming your speed and picture documentation is recorded.
The USPS will conveniently deliver a written readout for your records.
Put a piece of masking tape on the speedo with marks for the new known and verified speed.

Cheers

[The Mighty Gryphon]

If you want to avoid taking the cluster apart, there's a unique solution that is very accurate to determine speed.

Locate a school zone with a digital speed readout camera.
Motor through at the last known "GPS guessed" speed, in this case 70mph. (3 times is good for an average)
A light will flash in a stutter fashion, confirming your speed and picture documentation is recorded.
The USPS will conveniently deliver a written readout for your records.
Put a piece of masking tape on the speedo with marks for the new known and verified speed.

Cheers

LOL!!!

[rbm]

Yeah, but then you'd have to take the DMV to court to contest the accuracy of their equipment so that you have the assurance it was reading correctly at the time.  Hassle.

[natalena]

Yeah, but then you'd have to take the DMV to court to contest the accuracy of their equipment so that you have the assurance it was reading correctly at the time.  Hassle.

Good point.

Maybe it's better to just locate a radar-gun toting LEO, and see what your recorded speed is from the back of his cruiser.

[Martin]

When I lived in Victoria they used to have a screen that posted the speed you were doing situated between two towns. They had to readjust it so it didn't register after a certain speed, the local hoons were using it to see if they could outdo each other.  :laughing-on-ground:
Regards Martin.

[DavidATL]

I believe 60 hz input to the transducer on the final drive should result in 45 mph in a properly calibrated speedo.

I was researching this a couple of months ago and found a tip to use a soldering iron to induce a signal in the pickup:
https://ibmwr.org/index.php/1998/04/01/speedometer-calibrator/

They used 50hz as they weren’t in the US.

[billday]

There was a dandy piece of software some German guys created for calibrating K-bike speedos . . . I had it on my old laptop . . . anyone remember what it was called?

At one point when I didn't have a working speedo, I mounted a bicycle speedometer on my K. Calibrating that requires measuring the circumference of your front tire, which takes two people and a long tape measure but is not difficult. Later, when I had a working speedometer again, I found it really useful to have the bicycle unit too -- for getting accurate speed, plus a second trip odometer, thermometer, average speed calculator, etc.

[Laitch]

There was a dandy piece of software some German guys created for calibrating K-bike speedos . . . I had it on my old laptop . . . anyone remember what it was called?

Karamba.

[natalena]

At one point when I didn't have a working speedo, I mounted a bicycle speedometer on my K. Calibrating that requires measuring the circumference of your front tire, which takes two people and a long tape measure but is not difficult. Later, when I had a working speedometer again, I found it really useful to have the bicycle unit too -- for getting accurate speed, plus a second trip odometer, thermometer, average speed calculator, etc.

I wonder if this was a trend at one time, as the PO had a wired bicycle speedometer cobbled, when I bought the K75s. First thing I took off, as it was so ghastly duct-taped to the fairing with the wire dangling out.

[bizzaro]

If you want to avoid taking the cluster apart, there's a unique solution that is very accurate to determine speed.

Locate a school zone with a digital speed readout camera.
Motor through at the last known "GPS guessed" speed, in this case 70mph. (3 times is good for an average)
A light will flash in a stutter fashion, confirming your speed and picture documentation is recorded.
The USPS will conveniently deliver a written readout for your records.
Put a piece of masking tape on the speedo with marks for the new known and verified speed.

Cheers

 :giggles
I had to adjust mine.  And it still is about 3 or 4 miles fast. I think I need to max it out as stated in the link.  And yes,  soldering iron near the sensor (pop it out) should read about 45 MPH If I remember correctly.  There are several links here and about including rbm's. Clean and clear work space for disassembly is a must. Also low dust area.  Actually this is the one I used for guidance.  http://www.motobrick.com/index.php?topic=599.0

[cbelawn]

Thank you all for the incite. 

[The Mighty Gryphon]

Just curious, did you buy it from a pilot named Tom?  Should be a nice bike, he took good care of it.  The pilot thing with maintenance.

[cbelawn]

i did . Tom is a friend and neighbor. I have the records for work he had done.   

[The Mighty Gryphon]

He wanted me to buy it, but unfortunately with three bricks already, I had no room in the garage.  That bike should give you a lot of good miles.