So,

Trying to rebuild the electrics on this K75, getting precisely nowhere so any thoughts would be appreciated -


I got the bike as far as the starter turning over. I then went to reinstall the radiator / pipes etc. Once that was done i turned on the bike again and noted that the gear selector was not working nor the neutral light or the oil light. Basically the right hand side of the instrument cluster was dead. This also included the starter. I did find a relay fused open (load shed) which i replaced. So far i have checked
 - all the fuses
 - all the connections at the back of the console
 - every damn relay
 - stripped and rebuilt the right hand handlebar switch-gear
 - clutch switch

The switches on the right hand side are working - turn signal (including the green indicator on the RHS of the cluster) turn cancel, light switch. I checked the starter relay and i am not getting any voltage at the input pins. i am hesitant to short the relay to see if i can get the starter to turn.

I am hoping that someone might have an idea where to start trouble shooting - i got as far as pulling the plug from the electronic ignition module (i am trying to following the guide here http://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm) and could not see any voltage at pin 6 or 11.

Any thoughts on where might be the next best place to continue troubleshooting?

cheers

Ed

You seem to be describing a K75 with its shutoff (kill) switch activated. Is the lever in its vertical position? That's its start-enable position. Is 12V being received by it? Is 12V being output from it in the vertical position?

Does your rear brake-light work?

(First turn on the Key and set the Kill/Run to Run)

Take your Voltmeter and connect the black probe to battery negative (ground) and leave it there

Using the Red Probe, with Fuses still in place, touch it to the exposed metal tabs on each side of the top of the fuse

Use this method to check the voltage on BOTH sides of Fuse #1

If you get no voltage on EITHER side, then no power from the Kill/Run switch

If you get voltage on one side and not the other, the fuse is blown

If you get voltage on BOTH sides, that confirms the Green/Black power circuit that feeds the instrument panel is good (and your brake light should work)

(Different bike model in image below but principle is the same)

Thanks for the advice @Latich, @D'Ecosse. I will have another go at it this evening. I did notice that neither brake levers were activating the rear brake light. I did do a contunity check on the kill switch, which seemed to be working. I did suspect it was the kill switch thus me stripping and rebuilding it.

I did not check for voltages at the fuses. That seems a simple place to start so I will check that tonight.

I am understanding that the kill switch will output power to fuse one. If there is voltage at both sides of the fuse where would be the next port of call to test?. Also dumb question of the morning, fuse one = the top fuse?.

Another thing I noted, the load shed relay, that is normally energised?. When I press the starter button it should 'de-energise' ?
 

Thanks 

Ed

Load shed relay: that is correct. When you turn the ignition on there is a direct feed from the battery via the red and green wires on the ignition switch to pin 86 on the LSR. The other side of the coil (pin 85) earths through the starter motor windings (hence a bad earth here causing all sorts of grief elsewhere). Once you hit the start button, the 12 volt feed that goes to the starter motor is also applied to pin 85 on the LSR and it drops out (no more earth).

When you release the starter button there is a delay while the residual voltage in the starter motor windings disappears to earth. Once this has happened, LSR pin 85 can earth again through the windings and the LSR pulls in. The time taken for the residual voltage to go away is the time period between you releasing the starter button and the lights coming back on.

Thanks @Dai,


That's what i figured - i am slowly learning . At the moment precisely nothing is happening when i press the starter button. With the symptoms of the brake light not working and the instrument clusters not working it seems that there may be something going on with my kill switch?. This is from what i have learned from the responses above. 

My plan of attack is to see if i am getting power to fuse one - if not then it is the kill switch and i will try to trace back that wiring and see if i can see a problem. if there is power to both sides of fuse one I am not sure where to go from there - i will try to follow the wiring on from there and see if there is a break. It could be possible that there has been a wire or socket dislodged that is going into the relays?. 

I must go and get another battery for my multimeter - i think that will be the next damn thing to stop working. 

Ed

edmundf wrote:I did suspect it was the kill switch thus me stripping and rebuilding it.

What was needed to rebuild it?

I had the 'old' one - the replacement switch was a bit gummy so i took it apart and cleaned it out. I figured that there was a bad contact someplace. The switch was disassembled to component parts, all the copper contact pads cleaned and reassembled. The switch mechanism is much crisper now.

edmundf wrote:I had the 'old' one - the replacement switch was a bit gummy so i took it apart and cleaned it out. I figured that there was a bad contact someplace. The switch was disassembled to component parts, all the copper contact pads cleaned and reassembled. The switch mechanism is much crisper now.when I

You replaced one switch with another that you had cleaned. This guide was useful to me, using Google Translate. Perhaps you used it, too.

edmundf wrote:.... At the moment precisely nothing is happening when i press the starter button. With the symptoms of the brake light not working and the instrument clusters not working it seems that there may be something going on with my kill switch?.  

Yes, that is why I asked about the brake light, that is another simple quick indicator off the same power circuit on output side of Fuse 1.
And the Start switch won't work unless you have that circuit powered - even discounting the start enable via the neutral enable (which requires the Instruments to be active), if the clutch was pulled that would also couple the Green/Black circuit power (output of Fuse 1) directly to the start switch from output of clutch switch (on Black/Green to the start switch)
So all the evidence points to either simply the Fuse, or more likely the Kill/Run Switch
You can confirm you have power into the switch by checking for 12V on the green wire on the Switch connector

Here is simplified schematic for you

Thanks for all the help, hopefully i will find out in a few hours, just have to escape from work first . i will update shortly

So home, no voltage at the fuse. Pulled the rh switch off the bike and the instrument panel lit up. Appears I have a break someplace in the loom :/. When I move it the cluster goes out. Move it again and it comes back on. Hmmm. Also no voltage at the starter solenoid, yet.

Investigation continues.

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Success!

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Congrats
So what did you find?

I think it was an intermittent connection at the plug for the rh switch gear. Careful cleaning and it seems to be stable now. Tomorrow, air box and then the tank. Perhaps even an attempt to start it!

Thanks again for the help

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Just wondering how this K75 project is coming on...............

Edmund don't forget to come to Stradbally Fayre [M7, exit 16 on to N80 Carlow, 10km to Stradbally and its on your left as you enter Stradbally] on 27th December for Kristmas Brunch and pudding. Come on or in anything, just come along. 11am meet up, usually head off about 1:30 so we travel in daylight and get home for family things.

The bike has just made its way on the back of a trailer to a mechanic so hopefully they will be able to figure out why there no spark . I got as far as I am either being an idiot or one of the computers are FUBAR.

I shall update and as soon as it is running again I shall absolutely join you lot on a ride.

Ed

Hopefully won't be a big issue. I did send a PM saying we cold probably find units to swap out.....we know there are spares around and they only take a moment to swap.

Tell us where you are too, lots of Ks around Dublin.......

Interim update, it appears all the coils (pick up coil?) in the bike are gone, the ECU seems to be okay for the moment. It was noted that the rear shock is also gone, so research begins on that. I am hoping that the bike will come back with all the electrical gremlins gone and just the oily bits left to fix. I am located in D8 - not too far from St. Patrick's Cathedral. @Olaf, thanks for the PM!

Ed

As the K75 has three coils be very sure the earth to them is good and that the signal into them is good. They do fail.

I'm pretty much useless in the electrical department but I have some experience with riding on an OEM shock used past its due date by decades.  The replacement was a Ram shock from Realm.  Can't say enough good about it.  It had a massive positive effect on handling.  Better yet, I get to tell everyone here in the colonies that it is 'bespoke' when I am pointing it out in all its red coil spring glory.  There are other good shocks too though.

Woodie
(bespoke isn't a word that is used in these here parts)

As for rear shock....look out for YSS Y series, its a budget but very good shock and comes with 2 year warranty. If you want better there is a Z series but the Y series is excellent. Buying a used BMW OE shock is a waster, dead money as it wont last.

Thanks for the advice @Olaf - currently the bike is still the the garage, it got caught up with the Christmas madness so will probably not be looked at (further) until January. 

Happy Christmas everyone!

Woodie wrote:I'm pretty much useless in the electrical department but I have some experience with riding on an OEM shock used past its due date by decades.  The replacement was a Ram shock from Realm.  Can't say enough good about it.  It had a massive positive effect on handling.  Better yet, I get to tell everyone here in the colonies that it is 'bespoke' when I am pointing it out in all its red coil spring glory.  There are other good shocks too though.

Woodie
(bespoke isn't a word that is used in these here parts)

Those RAM shocks are good stuff but it 's important to get the right spring rate for the majority of your riding. When I tried a RAM shock on a K75 the spring that came with it was for 2-up, fully loaded riding and was WAY too stiff for riding solo with no luggage on a K75.  I contacted them and got a spring with a lighter spring rate and after that the shock worked "perfectly."

The 'bespoke' part of that shock for me was that I was asked about my weight, my riding style (commuter, spirited or touring - I chose the fourth option: spirited commuting), and whether I rode with a passenger much.  The shock, as it was set up by Realm, was a huge improvement.  I have yet to change any of the settings but I will likely try this in the 2019 riding season.  The cool thing about the shock, attested to by Duck, is that it can be modified to suit even if the needs have changed.

edmundf wrote:Thanks for the advice @Olaf - currently the bike is still the the garage, it got caught up with the Christmas madness so will probably not be looked at (further) until January. 

Happy Christmas everyone!

So why don't you come down to Stradbally Fayre on 27 December, we meet there for Christmas Brunch, 11am to about 1:30pm. Just down M7 to Junction 16 exit N80 towards Carlow, after 10km you hit Stradbally. Stradbally Fayre is on the left as you come into Stradbally, you will see fire station on right hand side. We don't go ride out that day as its just sociable so come on 4 wheels. You will be home by mid afternoon.

@Olaf - thanks for the invite. I should be able to make that .

Re the shock - hopefully this will be for touring, loaded 2 up, investigating the ferry to Santander assuming there is a lot of progress on the bike in the new year.

I have used the K100RT 2 up with YSS shock, its more than fine. When are you planning that trip? I have booked Cork Roscoff 1st June but will be down in south west France. Will Crean was on the ferry to Santander a few weeks ago and is coming along on 27th.

One up, two up with a ton of luggage, it is the spring that handles that rather than the make of the shock.

BobT wrote:One up, two up with a ton of luggage, it is the spring that handles that rather than the make of the shock.

Why have a shock at all then if all you need is a spring?

(Rhetorical question.)

Interestingly it is the shock that is gone not the spring. I will admit the lack of a spark is a more pressing concern at the moment. From my limited knowledge of bike and more so of shocks the choice would depend on what sort of driving style you have and what you like to use the bike for (have you seen Irish roads?  ) .

 i have noticed that there is some 'interchangability' with the term 'shock' and 'spring' referring to the entire suspension unit as opposed to the individual components of the suspension unit.

duck wrote:

BobT wrote:One up, two up with a ton of luggage, it is the spring that handles that rather than the make of the shock.

Why have a shock at all then if all you need is a spring?

(Rhetorical question.)

Who said that all you need is a spring? Olafs post was about load on the bike, and the spring is the thing that handles that.
Your post is aggressive, why?

If you do decide on the RAM shock, I can recommend that you use an oversize washer on the outside of the lower mounting to prevent vibration damper migration.  I have a RAM shock on my K75 and discovered this summer that the lower shock eye had slid halfway off the rubber vibration damper. I removed the shock and reseated the vibration damper back into the shock's eye by squeezing in a vice.  I then remounted the shock, this time using an oversized washer between the shock eye and mounting bolt to prevent the damper from migrating again.

https://photos.app.goo.gl/4SwweAEzQN9KUGAk9

robmack wrote:If you do decide on the RAM shock, I can recommend that you use an oversize washer on the outside of the lower mounting to prevent vibration damper migration.  I have a RAM shock on my K75 and discovered this summer that the lower shock eye had slid halfway off the rubber vibration damper. I removed the shock and reseated the vibration damper back into the shock's eye by squeezing in a vice.  I then remounted the shock, this time using an oversized washer between the shock eye and mounting bolt to prevent the damper from migrating again.

https://photos.app.goo.gl/4SwweAEzQN9KUGAk9

This is important and the only reason I say that is my K100LT came with oversize washer and I realised why it was there but had completely forgotten this until I read Robmack's post. But I am inclined to think such a washer should be there OEM?

edmundf wrote:Interestingly it is the shock that is gone not the spring. I will admit the lack of a spark is a more pressing concern at the moment. From my limited knowledge of bike and more so of shocks the choice would depend on what sort of driving style you have and what you like to use the bike for (have you seen Irish roads?  ) .

 i have noticed that there is some 'interchangability' with the term 'shock' and 'spring' referring to the entire suspension unit as opposed to the individual components of the suspension unit.

The rear suspension on a K bike is a combined shock absorber and spring assembly (with a single nut & bolt that attaches it to the frame at the top and nut and bolt which attaches it to the swing arm at the bottom)  - unlike the rear suspension on a typical car where the spring and shock parts are separate parts. Either way, they perform the same function - the spring takes the load and provides the cushioning effect, while the oil & gas filled shock absorber provides the dampening effect to make the ride smoother. With just a spring, the ride would be very bouncy. Usually, the whole assembly is referred to as the "rear shock".  The oil/gas filled shock absorber is the usual part to fail - the chromed piston can suffer from corrosion towards the top where is exposed to the elements (becoming rough and pitted) - when you hit a large bump (or if you don't adjust the spring compression for carrying a pillion or lots of camping gear), the shock may be compressed much more than usual and the rough corroded part tears the oil seal. Net result - the shock absorber loses oil and loses it's dampening effect. It is important that your shock assembly is fitted with the right size spring for your normal load (i.e your weight, the weight of stuff you carry and the weight of the pillion). That sets the datum and ride comfort - but you can adjust the spring tension manually for different load conditions like adding camping gear or a pillion. On many shocks, you can also adjust the dampening effect - the choice has much to do with your riding style. The Realm guys are really helpful in this department. 

As Robmack says, do fit an oversized washer on the mounting bolt - I have experienced the same "extrusion" of the vibration damper on my K100LT's. Easily fixed - but even more easily avoided.

That same sideways wandering happened on the Bitubo shock on my K100RS. After pressing the rubber bit back into the eye a 'fender' washer cured the problem.

Latest update,

It appears that the second hand hall effect sensor i got a few months ago is not working - i am trying to see if i can get a replacement. It appears that this will be a long journey to get the K back on the road

You've got two solutions to that problem (hopefully!). Make one good pickup out of the two, if you can identify the faulty parts (that's the 'hopefully' bit). The second option is to get two CYHME56 pickups and fit them: http://www.hallsensors.de/Hall-Vane.htm.

@Dai, not a bad plan! - although the bike is currently in the garage so it will require another transport charge to bring it back. I am hoping that the mechanic is correct about the hall sensor and that this is not a wild goose chase

latest update - the K now as a spark!. I am hoping that Eugene can get the engine running. From there it should be more straightforward mechanical bits from here on out. So progress

Now we have hope!! This is good news....!!

Yep, he just called, seemed to get the engine running quite easily after that. He is saying that the throttle cable is too short? As in it is not allowing the throttle to close completely.

Which model K75 have you?

There are two cable lengths for the K bikes, one longer one for all RT and LT versions of K75/100/1100, shorter one goes on all the others like Basic/S/C/RS.

If yours is a K75RT it is possible it has the shorter cable by mistake in which case a swap will be needed.

But make sure its correctly routed and not obstructed in case that's the cause.

I have the stock K75. I am going to call over later today and get the full story. It may be as simple as I did not fit the cable properly!

There's actually six different lengths of K75/K100 throttle cables:

32731457014 993mm <6/86
32731457376 1025mm >6/86
32731457016 1110mm <6/86
32731457378 1142mm >6/86
32731457015 937mm <6/86
32731457377 969mm >6/86

The first four of those part numbers show in the parts catalog for a standard K75.

According to realoem.com i have 
Series; K569 (K75, K75 C, K75 S, K75 RT) 
Model; K 75 85 (0562,0571) 
Market; EUR
Prod Month; 11/1991
 
which gives me;

01	Accelerator bowden cable	L=1025MM	1	06/1986		32731457376	$40.69
	FOR HANDLEBAR BOARD HIGH
01	Accelerator bowden cable	L=1142MM	1	06/1986		32731457378	$30.54		+core

which gives a difference of 117mm - sounds a lot which is why i am thinking i may not have fitted the thing correctly

FYI: Unless it's worn off all cables have the part number printed on them.

The 1142mm cable is the one that came on K75RTs so unless you have the high handlebars like the RT/LT models then the shorter 1025mm one is probably the right one for your K75 standard.

@Duck 

the cable was pretty badly burnt and has since gone into the bin so no luck there. I am thinking that it is the right cable, further investigations are required.

Sorry I hadn't checked and assumed two lengths like the clutch cables. Lesson to self....