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?

Depends on the endgear and the tyre in the back.


(Topic moved to a more suitable section)

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

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.

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

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.

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?

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

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



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

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.

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.

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

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

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

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.

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?

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

All correct Bill.

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.

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.

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.

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.

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/

Goodo, I'll check it out.

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

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.

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.

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

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

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.

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

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

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.

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:



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?

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.