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Thread: speedometer calibration on R bike

  1. #1
    petez
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    speedometer calibration on R bike

    Is it possible to calibrate the speedometer on an oilhead R bike? I have seen many methods for doing this on K bikes.

  2. #2
    Blocking the slow lane
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    I used to just multiply all my speedo readings by 0.9......actually, with my LT, I still have to.
    Jon Diaz
    BMW K75/K12GT
    BMWMOA Ambassador

  3. #3
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    Originally posted by jdiaz
    I used to just multiply all my speedo readings by 0.9......actually, with my LT, I still have to.
    Jon,
    Wouldn't that be an 11% error? That's a tad high isn't it?
    Frank G.
    Hattiesburg, Mississippi
    2004 R1150RT

  4. #4
    Blocking the slow lane
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    Originally posted by Mr. Frank
    Wouldn't that be an 11% error? That's a tad high isn't it?
    It depends. In the engineering world, we call that "tolerance," not error. Kinda like those exit polls that have a range of confidence.
    Jon Diaz
    BMW K75/K12GT
    BMWMOA Ambassador

  5. #5
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    Originally posted by jdiaz
    It depends. In the engineering world, we call that "tolerance," not error. Kinda like those exit polls that have a range of confidence.
    Tolerance is in both directions. BMW speedos are always off in the same direction by about the same percentage. That's German engineering.
    Frank G.
    Hattiesburg, Mississippi
    2004 R1150RT

  6. #6
    In need of a nap. paper's Avatar
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    I tossed my GPS in my tankbag to do a speedo test on my R1100R and was amazed with how accurate it was.
    It was never off more than 2 mph at speeds between 20-100 mph..
    It was worst at 30 where my speedo showed 30 and the GPS was at 28. At 100 it was only 1.3 mph off..
    This was with my Magellan SportTrak Pro with WAAS...
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  7. #7
    El Cheapo cat0020's Avatar
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    From my experience, GPS unit can vary on their accuracy.
    depending on the refresh rate of the GPS signals, it may take up to 3 seconds before the GPS calculates your speed, so the speed that's displaying on your GPS unit could very well be your speed 3 seconds ago, rather than instant speed.

    My R1150RS' speedometer is usually 5-7 mph faster than my Garmin Streetpilot displays on the screen. as the speed gets up to the triple digit, the difference between the two becomes smaller.




    Originally posted by Paper
    I tossed my GPS in my tankbag to do a speedo test on my R1100R and was amazed with how accurate it was.
    It was never off more than 2 mph at speeds between 20-100 mph..
    It was worst at 30 where my speedo showed 30 and the GPS was at 28. At 100 it was only 1.3 mph off..
    This was with my Magellan SportTrak Pro with WAAS...

  8. #8
    In need of a nap. paper's Avatar
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    You could be very right about the refresh rate, but this was done on a straight, flat road with my ThrottleMeister and looking back and forth between the speedo and the GPS.

    All speeds were actually held for about 15 seconds as I glanced back and forth between the two to make sure what I was seeing would be correct.. OK... At 100 I might have been in a little more of a hurry than 15 seconds..

    I didn't do this to post it here for your reading or questioning. I did it 2 months ago to find out where my speedo stood in the real world of speed... Or even more so, in the real world of tickets.. Also, I was getting 8 to 10 satellite's information during the entire test.

    I did the exact same thing with my Toyota T100 and my VW GTI..
    The most amazing part of this was that my BMW has the most accurate speedo.. OK.. Both the car and truck aren't running stock tire sizes, so I'm sure that is a huge factor on them... :cool:
    2005 R1200GS 1985 R80 1981 R65
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  9. #9
    El Cheapo cat0020's Avatar
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    Originally posted by Paper
    All speeds were actually held for about 15 seconds as I glanced back and forth between the two to make sure what I was seeing would be correct.. OK... At 100 I might have been in a little more of a hurry than 15 seconds..
    At 100 mph, traveling for 12 seconds.. that's close to 1/3 mile.
    I know there isn't much straight and flat roads near my area to safely do that kind of speed and see what's ahead.


  10. #10
    In need of a nap. paper's Avatar
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    Cat0020,
    Ever been to IL?? Rural IL??
    Nothing but one mile squares.. Flat one mile squares. At that time the fields were only tilled with nothing even planted yet..

    I appreciate your concern for my safety and your questioning of my experiment, but unless you were there, I don't understand why you don't believe me.. I have absolutely no reason to lie. I only told you my findings between my GPS and my speedometer.

    Send my your Garmin and I'll do it again, or even better come on over to IL and ride next to me..
    2005 R1200GS 1985 R80 1981 R65
    2004 Triumph Sprint ST
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  11. #11
    El Cheapo cat0020's Avatar
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    No offense Paperman, I'm just jealous not have the luxury of nice, flat, straight roads that allow me to open throttle and be safe or keep my license. Good for you.

  12. #12
    In need of a nap. paper's Avatar
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    Testing the speedo is the ONLY thing that flat straight roads are good for.. They suck for everything else.. BAD!!! Unless you like flat spots across your rear tire.

    Lucky for me, Southwestern Wisconsin is a fantastic area of curvy, hilly roads with little traffic. And it's only 1 hour away from the good stuff. I go over there just to put wear on the sides of my tires.
    2005 R1200GS 1985 R80 1981 R65
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  13. #13
    100,000+ miler 32232's Avatar
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    Speedo error

    A friend who is a local police officer verified my speedo error using radar. Results for a 2001 R1150r were as follows: 80km/h indicated was actually 76km/h, 100km/h was 93km/h, and 120km/h was 111km/h. To convert to mph multilpy by .62.
    Dave

    '06 Triumph Scrambler (Trans-Labrador veteran)

  14. #14
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    Speedo errors

    My '95 R11GSA was 5 mph fast according to police radar and Garmin III GPS.
    My '97 R11RA was 5 mph fast according to same.
    My '02 R1150GSA was 7 mph fast according to Garmin III and Garmin 176 and radar readings. On the '02 GS I put a speedo hub with the 3.0 gear ratio on the front from an R11RA and it brought the reading to only 2 mph fast.

    Andy
    Jennings, La.

  15. #15
    petez
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    Judging by the responses, no one knows whether it is possible to adjust the speedo on an R bike. A friend has one, so I will take it apart and see whether it is similar to the K-bike's instrument.

    I was able to adjust my K1100 to be absolutely correct at 60 MPH by tweaking an internal potentiometer.

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