BMW K bikes (Bricks)

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1Back to top Go down   85 K instrument reading Empty 85 K instrument reading on Sun Oct 25, 2020 3:28 pm

arbalest

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When your tach and speedo needle are both vertical, how fast are you going? My K100 (while I still had it), when the needles were vertical, my speedo read 100 mph. Mine was the only one I ever saw like that. Was that unusual?

    

2Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Sun Oct 25, 2020 4:55 pm

Arlina

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Depends on the endgear and the tyre in the back.


(Topic moved to a more suitable section)


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85 K instrument reading Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde - K75LT project
    

3Back to top Go down   85 K instrument reading Empty Instrument reading on Sun Oct 25, 2020 6:58 pm

daveyson

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Normally in fifth the needles are parallel, so when vertical 120km/h (~75mph) and 5,000rpm.



Last edited by daveyson on Sun Oct 25, 2020 7:35 pm; edited 1 time in total


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

4Back to top Go down   85 K instrument reading Empty 85 K instrument reading on Sun Oct 25, 2020 7:15 pm

arbalest

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Every other K bike I have seen shows 80 mph in the vertical position. I don't remember the rpm number. Mine is the only instrument showing 100 mph in the 12:00 position (that I have seen). My K was built in Oct 84.

    

5Back to top Go down   85 K instrument reading Empty Instrument reading on Sun Oct 25, 2020 7:53 pm

daveyson

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Were the needles always parallel in fifth? Can you post a pic of the instrument cluster?


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

6Back to top Go down   85 K instrument reading Empty 85 K instrument reading on Sun Oct 25, 2020 10:04 pm

arbalest

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Unfortunately, no. The bike is lost to me. If you look at an 85 or later U.S. K100, 80 (mph) is in the 12:00 position. On mine, 100 (mph) was in the 12:00 position.

    

7Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Sun Oct 25, 2020 11:20 pm

robmack

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The later instrument clusters had 100MPH at 12:00, the early gauges had 80MPH at 12:00. Did someone change the gauge cluster on your motorcycle at some point in its life?


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

8Back to top Go down   85 K instrument reading Empty 85 K instrument reading on Mon Oct 26, 2020 6:57 am

arbalest

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Not that I know of. I bought the bike with 3x.xxx miles.

    

9Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Mon Oct 26, 2020 12:51 pm

robmack

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Here is a picture showing the two styles of gauge clusters that were used on various K-bike models:

85 K instrument reading S-l1600

You might be able to recognise the one you had on your bike from this lineup.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

10Back to top Go down   85 K instrument reading Empty guages on Thu Oct 29, 2020 1:49 pm

arbalest

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What is the difference between the two guages on the left? Mine was definitely like the ones on the left. My build date was Oct. 84, if I remember right.

    

11Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Thu Oct 29, 2020 1:52 pm

robmack

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This photo came off Ebay and illustrates a seller offering three late-model gauges and one early-model gauge.
It was what Google presented to me when I did a search.

Based on your reply, the original '84 cluster on your bike was replaced with a late-model gauge cluster, either from a K100-16V or a K1100, at some point in its life. That explains why your bike was different that others you have seen.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

12Back to top Go down   85 K instrument reading Empty guages on Thu Oct 29, 2020 2:07 pm

arbalest

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The cluster must have been replaced early. The bike only had 36k miles on it when I bought it.

    

13Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Thu Oct 29, 2020 7:01 pm

indian036

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@arbalest wrote:The cluster must have been replaced early. The bike only had 36k miles on it when I bought it.
Perhaps more accurately, the instrument had 36k miles when you bought the bike. You would likely have no way of knowing what was on the removed instrument at changeover, nor whether the replacement was adjusted to match the original at the time, or in some other way.
One of my bikes also doesn't have the original instrument, so the odometer (when I fix it) is only helpful in determining service intervals and likely fuel level before the light comes on.

Bill


__________________________________________________
1985 K100RT  VIN 0028991  My original Very Happy   (Historic rego)
1985 K100RT  VIN 0029036  BOB the Blue Old Bike  (Historic rego)
1990 K100LT  VIN 0190452  Work in progress
1984 K100RT  VIN 0023022  Work needing lots of progress

1986 K100RT  VIN 0090542  Work needing lots and lots of progress
1993 K1100LT  VIN 0183046  Work in progress
1993 K75S  VIN 0213045  Newest toy, slightly non-original
    

14Back to top Go down   85 K instrument reading Empty 85 K instrument reading on Thu Oct 29, 2020 8:09 pm

ssk75rt

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My 2 cents worth; my 95 K75 instrument cluster does not match any of the four in the photo. In 5th gear the 12:00 position is 120 Km/hr and the tach is at 5500 rpm so not quite the same as what Daveyson reported. I know my instrument was replaced when the odo read 80K Km (or so the previous owner said. so it is not the original but came off an older K bike he had for spares but I do not know the details.

I have never tried to measure how accurate my speedo is but generally, when I go through the radar display, it is usually within +- 5 Km/hr

    

15Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Thu Oct 29, 2020 9:17 pm

robmack

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Those pictures show US clusters. Since we are both in Canada, I am going to make a leap of faith and assume that your speedo is calibrated in KPH, not MPH. Therefore the 100 mark on the dial would be equivalent to where the 60 mark is on the picture. The same guts are in the clusters for all markets, just the dials change.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

16Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Thu Oct 29, 2020 10:17 pm

Laitch

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@robmack wrote: The same guts are in the clusters for all markets, just the dials change.
Are you indicating that the guts of the four instruments pictured in Reply#9 are the same?


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1995 K75 81,000 miles
85 K instrument reading Usa-lo10
    

17Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Thu Oct 29, 2020 10:30 pm

indian036

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The dial driver mechanism will be slightly different to accommodate a needle movement of nearly 270 degrees compared to a bit over 180 degrees.
Other variations relate to

  • whether the fuel warning is of the older 2 light type or the newer 1 light type, but all those in the picture are the later 1 light type
  • if the primary/sole speed is in km/h, in which case the gearing for the odometer and trip meter will be different to read km, not miles. Again, none in the picture are km odometers.
  • I understand, though I haven't confirmed personally, that within the same odometer unit types (miles or km) there are variations in the gear combinations to get the same result.
  • slightly different pin shapes on the connection at the back of the meter. I suspect that all pictured will be the later type as well.


Bill


__________________________________________________
1985 K100RT  VIN 0028991  My original Very Happy   (Historic rego)
1985 K100RT  VIN 0029036  BOB the Blue Old Bike  (Historic rego)
1990 K100LT  VIN 0190452  Work in progress
1984 K100RT  VIN 0023022  Work needing lots of progress

1986 K100RT  VIN 0090542  Work needing lots and lots of progress
1993 K1100LT  VIN 0183046  Work in progress
1993 K75S  VIN 0213045  Newest toy, slightly non-original
    

18Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Thu Oct 29, 2020 11:20 pm

robmack

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All correct Bill.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

19Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Thu Oct 29, 2020 11:23 pm

robmack

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@Laitch wrote:
@robmack wrote: The same guts are in the clusters for all markets, just the dials change.
Are you indicating that the guts of the four instruments pictured in Reply#9 are the same?
No. I meant that all early models, whether KMs or Miles, have the same guts essentially, except for odometer gearing. But between early and late types, different. Sorry I wan't clear. Bill's post got it right with the differences. I was lazy with my wording.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

20Back to top Go down   85 K instrument reading Empty 85 K instrument reading on Fri Oct 30, 2020 12:19 pm

ssk75rt

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Just to clairify Robmac is correct, the instrument dial is in KMH. I do not know what the original dial was displayed as but assume it was also KMH.

    

21Back to top Go down   85 K instrument reading Empty Instrument on Fri Oct 30, 2020 6:55 pm

daveyson

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Hopefully this is an OK time to ask,  the two extra lines at about 40mph, 80mph and about 135mph, what's that all about?

Ssk75rt, I'm thinking your instrument cluster will be the same as mine, but maybe a k75 is designed to rev a bit more cause it's a bit smaller engine. So maybe needles only close to parallel on a k75. I've also been guessing the speed sensor monitors the axle, so if swapping these different clusters around, the speedo is hopefully still accurate.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

22Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Fri Oct 30, 2020 8:46 pm

robmack

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@daveyson wrote:the two extra lines at about 40mph, 80mph and about 135mph, what's that all about?
Reflection of the lights off of the glass.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

23Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Fri Oct 30, 2020 8:54 pm

robmack

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@daveyson wrote:Ssk75rt, I'm thinking your instrument cluster will be the same as mine, but maybe a k75 is designed to rev a bit more cause it's a bit smaller engine. So maybe needles only close to parallel on a k75.  I've also been guessing the speed sensor monitors the axle, so if swapping these different clusters around, the speedo is hopefully still accurate.
The speedometer is electronic so it can be calibrated to show the correct road speed given variations in wheel circumferences. the number of pulses per revolution is a constant, irrespective of the size of the wheel.

The speed of the bike is a function of the circumference of the rear wheel (tire + rim) and the number of pulses per revolution.  The correspondence between the engine RPMs and speed is a function of the ratio of the final drive and the selected gear in the transmission.  So, on different K-bike models, different RPMs of the engine at a selected gear will give you  a selected speed.  See Largiader's web page to see this graphically.  http://www.largiader.com/articles/gearing/


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

24Back to top Go down   85 K instrument reading Empty Instrument on Fri Oct 30, 2020 10:42 pm

daveyson

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Goodo, I'll check it out.

Any ideas out there about the extra lines on the speedo?


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

25Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Sat Oct 31, 2020 12:19 am

Laitch

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@robmack wrote:
@daveyson wrote:the two extra lines at about 40mph, 80mph and about 135mph, what's that all about?
Reflection of the lights off of the glass.
Spooky! Those are intervals of enlightenment whereby if the rider maintains speed within them for long enough without an excessively whirr-ey gearbox, clarity will enter consciousness though the riding jacket vents.
85 K instrument reading Scree112


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1995 K75 81,000 miles
85 K instrument reading Usa-lo10
    

26Back to top Go down   85 K instrument reading Empty Instrument on Sat Oct 31, 2020 2:04 am

daveyson

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Oops, missed the earlier reply.

I've looked at the speed/revs graph in the riders manual to find a pattern with the gears, but can't seem to get a meld.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

27Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Sat Oct 31, 2020 1:42 pm

robmack

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Have you tried Largiader's gearing web page I linked to in post #23?  It includes a graphing calculator.


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

28Back to top Go down   85 K instrument reading Empty 85 K instrument reading on Sat Oct 31, 2020 2:33 pm

ssk75rt

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Unfortunately I cannot ride with the vents on my riding gear open. Too cold...the cold air freezes the hair on my armpits and I cannot comfortably lower my arms. I shall receive enlightenment next season when the temperatures permit 85 K instrument reading 177381

    

29Back to top Go down   85 K instrument reading Empty Instrument reading on Sat Oct 31, 2020 4:11 pm

daveyson

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I just skimmed over the largiader site first cause it was looking too deep. Second time I clicked all the options in the k75 column (but mines a k100) each line is made up of three straight parts (but there are five gears) Dunno what all this means.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

30Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Sat Oct 31, 2020 4:31 pm

robmack

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You'll see a line at the bottom of the calculator reading "Display speed at 1200 RPM or 5000 RPM" where the 1200 and 5000 are links.  Click on one or the other and a graph will be constructed with the line superimposed on the grid.  That will give you the ratios between gear and road speed at a given RPM. Different graphs will get overlaid if you select different final drive ratios in turn or different grids will be presented depending on which RPM you select from those links above.

If you want an Excel spreadsheet version of this same calculation without the graphing, then download this workbook: https://drive.google.com/file/d/1muWnzWfPHE8kueUcOFloRLZO5YJ6dnbV/view?usp=sharing


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Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

31Back to top Go down   85 K instrument reading Empty Instrument reading on Sat Oct 31, 2020 4:39 pm

daveyson

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Good one thanks, I'll have a better look when I next get to a computer. My phone is running out of space.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

32Back to top Go down   85 K instrument reading Empty Instrument reading on Sun Nov 01, 2020 1:09 am

daveyson

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After clicking on the 5,000rpm I still don't get it. Dunno why third gear seems to have no effect either.

Haven't yet looked at the last link though.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

33Back to top Go down   85 K instrument reading Empty Re: 85 K instrument reading on Sun Nov 01, 2020 1:30 am

robmack

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Maybe I'm misunderstanding your expectations. I clicked on 2.91 (32/11) under the K75 column and got the brown graph.  Then I clicked on 5000 RPM and got the grid.  It drew the following graph:

85 K instrument reading Screen11

This graph tells me that in third gear, at 5000 RPM, with standard BMW wheels mounted on a 32/11 final drive unit, my bike should be travelling 55 MPH.  With all the same conditions, but now selecting 4th gear, the bike should be travelling at 68 MPH.  In 5th, 77 MPH.

I'm sorry, am I missing something that you are looking for?


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

34Back to top Go down   85 K instrument reading Empty Instrument reading on Sun Nov 01, 2020 1:38 am

daveyson

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I'm wondering why the speedo has extra lines at 40mph, 80mph and about 135mph? Where Laitch has pointed to. To muddy the waters even more, the metric speedo is different again.

I've wondered if third would be the ideal gear between 40 and 80, and fifth gear above 80, if in a race?

Edit, just read on another thread that the speedo may have been checked for accuracy at different frequencies to fall within the extra lines.


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