SOLVE NOTE FOR OTHERS: For those with the same issue looking for a solution I'm popping it here for convenience. The issue quite literally was just poor contacts. I was on the fence about getting Deoxit as it was quite expensive and you need like a few drops of it but turns out can't beat the best and it fixed it almost immediately. Strong recommend you get the git with the bits because you're going into a few tiny crevices. This is what I bought from Jaycar. 


Got an almost entirely original 1984 K100 with 80,000km. Speedo was a bit how you going and would usually not work until I knocked on the cluster then it worked for a while


I opened it, took it apart and sealed it again just to have a look (everything worked fine but issues still persisted). 
Then I felt more confident and opened it a second time, just cleaned everything up, put it back together (still the same). 
Then felt emboldened, decided i'd try to resolve the moisture issues and the speedo issues properly that these are so afflicted by. 

1. I put some electric tape around the rim.
2. put a desiccant silica packet inside.
3. slightly torqued the 3 pins connecting the speedo cluster etc (the common fix to keep contact) and used some isopropyl and slightly buffed it for better contact using isopropyl.
4. did the same for the main plug interface (the two big wiring harness bits that plug from the bike into the back of the dash).

Now the speed won't show at all. Like at all, at all. Nada. 
All other instrument parts seem to be working. 


I don't know if I buggered something with the pins to the bike (i noticed that some are wobbly but I don't know if that's how they were before) and the 3 pin system seems perfectly fine so I have no clue. 


Where do I begin troubleshooting this? What can I do to try make it work again that isn't the usual go-to which I've already done. 
thank you 


Does anyone have any inkling on what to do? I'm at a loss and all I can think to do is to just disassemble the entire thing and put it back together. I'm wondering if I just forgot to reattach a ground or something. 

Also there was a single spare part which is wigging me out. It fell out, i have no idea from where but it looks like a tiny horseshoe. Can't attach photos but will do later.

The picture would help, but so will taking it apart and checking that all of the long pins are located correctly. It's easier than you think to misalign them and not get contact with one or more pins even if thay appeared to be aligned when pushing it back together. Wobbly pins is also not a good sign.

Got the photos working. I’ve just uploaded the one for now (sorry about the rotation).

I’m concerned the issue might be with the pins in the centre bottom part (the two columns of pins that connect the bike to the cluster) as the three pins at the top seem to be connected okay and that’s what connects to the speedo I think.

I think we need to see the bit that fell out.

The horseshoe thing is likely the circlip that retains the spring on the oddo trip winder knob

That's my thought too, in which case there may be a similar-sized washer and possibly a lightweight spring doing the rounds in the housing.

Well, I seem to have misplaced the horshoe item for the moment. I think I placed it somewhere to keep it aside and I've forgotten where for the moment. That being said, I feel like it's probably spot on with the piece being from the speedo dial for the odometer. 

You can see what looks like the piece here in this link though I don't seem to see the rest of the parts so maybe they are floating around inside? I have just taken it apart though and see no pieces anywhere. 




Here is a video and photos of more detail including the wobbly pin. It looks like it was resined down but that's broken. I don't think it was soldered on (See Video A in this link)

The photos below also just show close ups of the connection between the dial.

Pin 24. That's the feed for the instrument lighting. The only other thing that I can currently think of is that the needle might be scraping on the face. Or in all the fussing around, you might have accidently disconnected the speedo drive under the r/h sidepanel.

If pin 21 touches anything above 6 volts  it will stop the speedo from doing anything

On the signal amplifier board which drives the meter ,,, and the turn signal relay
There is a zenner diode  installed to protect the system  which will short out the drive signals

Had my new to me lunchbox off black betty changing green globes for leds , i accidently touch cables on flying leads to that pin    blue/ green  maybe     all speedo actions went dead

Had a replaxement on hand  for the fix

And made an externat board for terminations so it wont happen again... and not the first time its happened  ... last time it was getting the connector missaligned by 1 pin ...

Dai wrote:Pin 24. That's the feed for the instrument lighting. The only other thing that I can currently think of is that the needle might be scraping on the face. Or in all the fussing around, you might have accidently disconnected the speedo drive under the r/h sidepanel.

Alright, I don't think it's the needle but I will check it to make sure. Disconnecting the unit is totally plausible. I've got it half disassembled and I'm going to finish it and go over it with a fine tooth comb to check.

Needle is still moving as it did before when I manually move it (slowly returns to 0).

have disassembled the main apparatus but I can't see anything that looks disconnected or blown. 

Nothing looks out of sorts with the machinery itself so I'm still thinking cabling but I can't see anything wrong anywhere nor can I find a ground or something that should be plugged in but isn't. 

ark100 wrote:Needle is still moving as it did before when I manually move it (slowly returns to 0).

Have you removed and cleaned the speedometer pulse generator that is mounted into the rear drive and also cleaned its wiring connector?

I haven’t done that yet but given it was working until I reassembled it, would that make a difference? Should it be done anyway? What’s the procedure for cleaning these contacts? Same as the rest?

You should be able to probe the instruments loom pins 23 and 22 and measure a few hundred ohms ....being the speedo pick up  if not  you will need to clen the loom to speedo connector near the resevoir .... deoxit is your friend

ark100 wrote:I haven’t done that yet but given it was working until I reassembled it, would that make a difference?

Charlie has laid out a path for exploration.  It was working but was working slowly. Presumably, that is why you laid hands on the cluster's guts twice. Whenever failure occurs, I always start at the easiest point to investigate, no matter how unlikely it is—hence, the pulse generator.

The pulse generator is mounted into the drive with one screw; the generator must be carefully pulled out if it is to be cleaned and liberated from gunk that might be interfering with its function.

I use DeoxIT D5 electronic cleaner. The connector pins and sockets are also cleaned with electronic cleaner using a small brush, swabs and maybe even fine emery cloth. I always disconnect the battery ground when cleaning this stuff.

Laitch wrote:The pulse generator is mounted into the drive with one screw (...)

I've come across two versions of the pickup. One has a rubber boot on it and two screws to hold it together and the other is epoxy encapsulated and seems to be the most common type. If you have the one with the two screws, do not remove the screw in the side because the contacts will fall apart. It is the screw at the rear that holds it to the bevel drive.

In both cases, if it doesn't move relatively easily, get the penetrating fluid out. They can build up a ring of corrosion under the collar.

[Edit] Corrected the description of the screw-together one

Thank you, I'll order some deoxit and sort out a plan of attack. These instructions have been incredibly useful. Sadly I'm running about over the next 1-3 weeks up and down the east coast so I won't be able to give it a crack till I'm home but I suppose that will give me time to order some penetrator. Will update when I get back and have tried these things. 

Thanks all! Looking forward to this.


Quick question in regards to the deoxit. 
Does it have to be that brand? Is it D5 specifically? I've never heard of it outside of this project so I'm not sure. 

Would this do? (Deoxit 2ml)
Or, given the difficulty in finding Deoxit in Australia, can I use something like the following: 
CRC Contact cleaner or MG contact cleaner

Deoxit is available from most all jacar stockists throughout aus and nz

buenas tardes

 primero me dices que la aguja indicadora de velocidad si que funciona.

si es asi el problemas lo tenemos en el motor paso a paso o los engranajes

saca de nuevo el motor paso a paso pon el central de las dos bovbinas a un positivo y dale masa a un lado de la bobina y a otro en ese momento se debe de mover el motor (el engranaje mas pequeño)

comprueba la continuidad de los dos cables que salen desde la placa del circuito impreso a las dos bobinas.

si observas solo hay un integrado para mnover los dos motores el de la aguja de la velocidad y el del motor paso a paso, le electonica es muy dificil que se estrope.

si la señal llega desde la aguja el problemas el o de las bobinas o un problema mecanico

Okay, back home again and have been tinkering with everyones advice. 
AND IT'S FIXED! 

@komandoalicante, thank you for the help. I ran your message through a translator but ran into an issue when I realised I don't have a 12v power supply to test the motor. I did however, check the continuity of the board and it looked alright.

I put deoxit red to clean everything and gold to protect it and wired it all up and it's working again! 

Thank you so much for all the help. Can't wait to be out and riding and hopefully nothing else is wrong now that the moisture has been addressed. 


Lastly, while I was using deoxit on anything else I could find while the cowl was off, I wanted to double check some plugs incase any grounds had been forgotten.

I have these three plugs and I think they go on their respective spots where I've drawn arrows but there is the third which I have no clue. Is this a remnant for heated grips or something?

ark100 wrote:. . . Is this a remnant for heated grips or something?

Do the front indicators flash?

Yes, bit of a dumbo moment. It's obviously the plug for the indicators in the cowling. Durrr