Hi to the gods of electric,I recently had a car turn in front of me causing me to brake HARD(causing the front yokes to collapse)and smash everything including engine case which filled the timing chain with shards of alloy...now I've fixed it all but the wiring is useless. I've got the engine management loom with all relays...what I need to know is where do I add power to make it run ...living in Thailand the road laws are very different..the bike is a cafe design already and a great bike but I just need it to start and run ...please please please I can add lights later

I don't think I want to touch this question with a 10' barge pole.  "Beyond Here There be Dragons"

You were brave enough to even post that- Bravo!

Best advice I can give is to get a circuit for the model, which will give you the wire colours of the factory wiring then get someone who is local and has a working relationship with the electricky gods and sit down with them and the bike and make lots of notes.
I would not like to try to help from where I am and as Robmack said dragons and beware.

Hi Ribi, enjoy the ride. 

I wouldn't touch it with a 40 foot barge pole, luckily I'm in another country so it's up to you. 

When you say you haven't got power, I'm assuming with the key and kill switch on, and start button pressed, the engine doesn't crank. Yeah it sounds like we might be opening up a can of worms but here we go. 

No crank, simply the starter circuit isn't working, and that's a simple circuit, basically key, kill switch, start button, starter relay, starter motor, and battery. 

With the front end damage from the accident, possibly the start button on the handlebar or the wiring for it is the problem. The plug for the right handle controls is under the tank, on the right. Bypass the start button with a jumper wire between the black/green wires and the black/yellow wires (and/or bypass the kill switch) 

If your headlight also doesn't work (lights don't work?) maybe look at the battery, it's wiring, and the starter relay, since this is what the starting circuit and headlight circuit have in common. 

Or for example check for power to the key and power from the key. Check the wiring and connections.

What year is the K, and is it 75, 100 or 1100?


Edit; K75....

Grab some downloads here from my cloud;

https://mega.nz/folder/myg1QLiT#LTD5zuma8Ivv8l8IzCfPBQ

A few quick checks. When you turn the key on, you should hear a faint click from the relay box as the load shed relay turns on (and click again with the key turned off) If it clicks that means you have power to and from the ignition switch. 

With the key on, if the cluster lights come on, that means you have power to and from the kill switch. If no cluster lights, if you have power at fuse one, again the kill switch is good.

With a test light at pin 86 of the starter relay, you should have power with the start button pressed, that means you have power to and from the start button (or with the load shed relay removed, you should hear the starter relay click with the start button pressed)

Turn the lighting switch on (right handlebar) and the  headlight switch to low beam (left handlebar) then turn the key on. If the headlight was on low beam when you crashed, the filament was glowing hot, so would easily break. The tail and brake lights might also not be working for the same reason, since your brakes were on.

Turn the headlight switch to high beam and then the key on. If you have high beam that means you have power to and from the lighting switch, and the headlight switch. If no high beam, check for flash to pass, which doesn't depend on the lighting switch for power, unlike the high and low beam switches.

Very sorry the bike is 1986 K75,so maybe I confused you..firstly this is Thailand and there is no help I do this alone my biker friends don't have a clue they use Harleys as I said I ride a Buell,,so the wiring is not all here now and lights and horn can be added later../I have the engine management loom connected/I have a starter that works but I'm not sure how to put the power to IGN and fuel injection apparently pushing the start button sends the power to these ???I only have the shed and starter relay + bulb checker I don't have any handlebar controls(nothing)I have on/off rocker switch the IGN block packed up years ago so I just have a 2 wire on/off that worked for a long time.after crashing the starter button fell to bits and with the clocks smashed it showed green neutral light but in 4th gear I put together the 3 relay fix but fear I'd gone to far in my strip down to use it.i thank you all for your inputs I haven't got any type of barge pole so I will carry on/ I can't except some thing from 1986 can't work because it's not got all the bmw add ons

OK so I think it was going before the crash, so get it back to that stage.

You should have constant battery power to the ignition switch. 

Yes the fuel injection unit gets power after pressing the start button. When the ignition control unit gets a start signal, it provides earth to the fuel relay, which sends power to the fuel injection unit. 

Bert's guide is good for understanding how it all works, and is a trouble shooting guide to boot. From the portal tab, you will find it at tech pages/electrical/trouble shooting.



There's some better drawings at the tech pages.

Wiring diagrams:

http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/kwiring/Early%20K75%20K100/Early.K75C.Wiring.V4.0.pdf

http://www.kbikeparts.com/classickbikes.com/ckb.tech/0.ckb.tech.files/kwiring/Early%20K75%20K100/K75C.Wiring.Color(50%25).jpg

is the bike worth saving ? what sort of value is this in thai baht ?

Excuse me firstie but yes it is worth saving,,,to anyone else posting thank you very very much. All. Help is greatly appreciated off course it's worth saving

My opinion is that it would be easier to buy a secondhand wiring loom from a reputable breaker such as Motorworks. I rewire motorcycles for fun and I know exactly how complex that wiring loom is.

I note Dai's comment about the complexity of rewiring wiring looms. Various forum posts also tell us that published wiring diagrams often contain errors. Could I suggest that if you have done a successful rewiring job and drawn a circuit diagram of it that you submit it to our forum with details of the year and model of the bike it is for.

Adding to what Dai said.  You wrote  in the first post,  "I've got the engine management loom with all relays" after your crash.  That makes no sense what so ever, hence the reluctance for people to jump in and help.  The K75 wiring harness consists of two major parts - the main harness and the Fuel injector /  ECU harness.  The main harness contains all wires for all functions bundled together to implement fuel management, lights and indicators, start circuitry, engine operation,  and sensors for gauges.  So how the engine management functions magically sprang from the main  harness after the accident is a miracle.

My experience is that these K-bikes can prove to be difficult motorcycles to get going, even ones that are 90% or more stock.  Personally, I worked 30+ hours trying to debug a non-starter this summer and gave up with no success.  The solution to the problem eluded me and I still have no idea what is the root cause even after swapping nearly ever part in the electrical system.

The sugestions from people are to start from a well known state by replacing your suspect harness with a known good working one and then bring the motorcycle back onto its legs.  Alternatively, start at a good known state by scrapping your accident victim and getting a new used K-bike which demonstrably starts and runs.  Both of these suggestions eliminates various unknowns that will stymy your progress, especially since you have no knowledge of what unmentionable butchery the bike underwent when it was converted to a cafe racer.

i agree with the above , bike sounds bad 

I found it hard to trace the wires on the standard wiring diagram. So one of the Kronies enlarged a set and I had them laminated. Using a chino graphic pencil I can trace the wires with the pencil and tick them off as I go. Once the job is complete I erase the marking with wax and grease remover. It has made the whole job of tracing wiring heaps easier. I have a smaller version laminated to carry on the bike when needed.
Regards Martin.

MartinW wrote:I found it hard to trace the wires on the standard wiring diagram. So one of the Kronies enlarged a set and I had them laminated. Using a chino graphic pencil I can trace the wires with the pencil and tick them off as I go. Once the job is complete I erase the marking with wax and grease remover. It has made the whole job of tracing wiring heaps easier. I have a smaller version laminated to carry on the bike when needed.
Regards Martin.

 That is an awesome idea! I may need to do that for my 85 rs. I get myself all turned around as to what I have completed an what is left to complete.

You mention that the clocks are smashed.  How badly?  Have you replaced them or made repairs?  Are they original or does the bike have aftermarket instruments? 

Did you build this bike or did you buy it from someone who did?  Your posts make me think the wiring harness has been modified, and, in order to help, we need to know what was modified and how it was modified. 

I think it would be better to replace the harness to get the engine running.  Then, if you want, you can remove the wiring the bike no longer needs.  The collision can do damage to wiring in the harness that is very difficult to find.  There are many for sale on eBay by sellers who will ship to Thailand.  Just make sure it was removed from a running bike.  Some sellers will show videos of the bike running before it was parted out.

Thanks to all of you ,I bought the bike in total original state with original paint I cut it up keeping in mind how good it was I cafe with original wiring and oversized ugly bits out of respect to how good it was (I loved it)BUT then someone turned in front of me under hard braking the original yokes appear to have broken causing the front end destruction ..the gear was in digital 4 and neutral on the green light/ it also smashed right casing sheering the mounting bolts and depositing broken aluminium in the timing case..I've done all that and now I want it to start ..yes I've turned it by hand lots of times/I replaced the forks and yokes with gsx bandit 1000 yokes and forks with the bmw wheel and brakes...I cut the loom keeping load shed relay and 2 starter relays I had previously changed the original big relay with non bmw and it worked fine  thank you I love my k75 it's good for a trip I don't need top speed although it does fly ..in a previous life I worked on vw GTI which use the same system so I thought how difficult can it be.  It would appear to be difficult so I will carry on with what I have and hopefully find the answer or completely screw it up..ps I'm not in the position to just pay up but I have time  many thanks to you all happy roads

Hi guys,I have to say I'm totally shocked that I can't find the info I need !! How to run a k75 engine using only the wiring for the start and run (no lights and horn)what do you need to do in a boat or a Hillman imp someone must have done it /the bike was running when it crashed.....so I don't want to mess something up by trial and error like burning out ECU or ignition / is there anything I need to be aware of ?and a bit of help in connecting a starter button that fires power to the right place ..many many thanks for all of your inputs even the downers I've actually got a really good clean bike as it's never been in European weather

All I can do is refer you to a circuit for a K100 https://www.dropbox.com/s/3gc5ubtjjvpwmu3/K100%20Late.png?dl=0
What you are looking for probably does not exist here and the forums that are specific to cafe K100s or K75s is where the info will be if at all.

Looking at the wiring diagrams you will see the starter button sends power to the starter relay through a black/yellow wire. It also sends this cranking signal to both computers. Maybe start with your full loom that worked and disconnect one at a time.

Go one step at a time. For example does the starter relay get energised after pressing the start button.

If cranking, check for spark and fuel.

Posting some photos would help to see what's going on.

Hey daveyson Rick G, THANKS FOR REPLIES... DAVEYSON YOUVE GIVEN A VERY USEFUL CLUE MANY THANKS

I don't have a full loom sorry

If you want to understand the various sections of the wiring harness and how they are isolated from each other or interact with each other, then on this web site, on the portal page is a link to the tech pages. On the tech page is a link to Electrical diagrams.  You'll be brought to the interactive electrical diagram. The tabs across the top are various sections.  Press on starter and you'll see the wires that energize the starter and only those wires. This will help you to reach your objective to simplify the starter circuit.

Ribi wrote:I don't have a full loom sorry

Can you tell us exactly which components you know could connect to the remainder of the loom you do have, Ribi?

Yes sir, I am connected to a starter relay, a load shed relay,fuel injection relay/ I'm connected at the alternator and starter motor the engine harness is complete to ECU and IGN + hall sensor