Hello!

The last days my bikes (K75, 1991, 45tkm, no ABS, garage parked) ignition turns of while I'm riding, not very often. Just for a split second, I realize it while riding, there is no response from the Throttle for a split second. The warning light goes on, I have to use the hand break and rear break to turn the light of again.
I still can go on riding, happend only a few times.

A other issue I had once, was I could not start the bike, I turned the key and nothing happend, no light, no sound from the fuel pump.
After turning the key a few times it worked again and I could start.

I still can ride the bike, it runs except the issue, perfectly.
There are days without any issues.

I assume Cleaning the bike ignition switch could be a solution?!


What are your suggestions?

Cheers

Sounds like the ignition switch to me.

Same thing for me. Clean the switch and please report to us.

Or it could be the fuel tank connector. (Unless the dash lights go out too.)

Thanks for the help, guys!

I will clean the ignition switch and the fuel tank connector, but I will concentrate on the ignition.

I will use this:
Cleaning a K bike ignition switch
And in German Zündschloßreparatur

I'll report back, just give me 2-3 days time

Cheers

Chocolate wrote:I will use this:
Cleaning a K bike ignition switch
And in German Zündschloßreparatur

Thanks for the link Chocolate.
I was earlier looking for a similar link on the download page, but the web site is offline now.
I will replace it with this one.

Cheers and good luck solving your problem.

CF

yep a good guide to cleaning the switch

I have done similar to this ...with a very good result

keep at it , and good luck

it was the connector to the switch that was dodgy on mine.

Update:


I have cleaned the ignition switch, issue persist!

While riding the bike today, it suddenly shuts of, it starts again immediately, without pressing the start button, only turn the throttle, the warning light is on and I have to pull the hand break and push the rear break to turn it of again.

It happens about every kilometer.

What I did:

1.) Valves are checked and OK
2.) fuel filter and air filter have been changed
3.) I cleaned the motronic connection under the seat.

4.) I let it run, standing on the center stand.
After 5min it shut down. The lights where still all on.

5.) I have tested with the fuel cap open, same issue, it shut down after 4min, all lights still on, the engine stays of, until I press the start button, starts immediately. The bike was still hot from the ride through the city.

6.) pulled the cable a bit, at the right side where the handlebar is and all the cables are running. This doesn't make a different.
I was thinking about a bad cable.

7.) I would exclude a mass problem, since I cleaned the connection at the gearbox and tightened the batterie pols + -.
AND the watch is still running, if there would be a mass problem, the watch would show 0.00

8.) All fuses have been pulled and cleaned

I speculate, a electric issue?!

It seams to get worse.
The pump inside the tank works, as long as it runs

I don't think it is heat related?!


What else can I do?
I'm a bit concerned riding the bike in this state.

Cheers
And the weather is so nice ;-(


I'm following this threat, seams to have similarities.
Help--bike starts and dies--already changed Hall Sensor, Fuel Pump, Filter and Cleaned Computer Connections

The ignition switch is the most likely thing and if that is proven OK then electrical connections that are associated with power feed to the ICU and ECU

I think it would be a good idea to check the kill switch as the next step.
Then the connector for the RHS switch assy under the tank.

Inge K. wrote:I think it would be a good idea to check the kill switch as the next step.
Then the connector for the RHS switch assy under the tank.

nods head

Did you ever pull the spark plugs and report back on your findings (dark and sooty, or dry and ashy, etc).

This can provide a clue of direction for troubleshooting.

Chocolate wrote:I have cleaned the ignition switch, issue persist!

While riding the bike today, it suddenly shuts of, it starts again immediately, without pressing the start button, only turn the throttle, the warning light is on and I have to pull the hand break and push the rear break to turn it of again.

It happens about every kilometer.

The fact that the brake warning light has come on means the BMU has reset itself. It will only do that when the ignition/power has been cut. So it has to be a fault in the ignition switching or connectors or wiring somewhere.
The ignition switch is usually the culprit but if Choco has cleaned the ignition sw. then the fault probably lies somewhere else. However, there are some delicate bits in that switch like the 4 little springs and the ball bearing. If some of this is missing or not assembled correctly then the switch contacts may not be meeting properly. Just a thought.
Here's a post with pics of the inside of my ignition switch
I have found that the kill switch can suffer in the same way.

Thanks all, very much.

I will go on and perform the ideas given here.
Since I got a brand new ignition switch, I will try that to.

I'll tell you how it worked out

Cheers

If you've fitted a brand new ignition switch and the symptoms have not changed then look elsewhere.

Inge K. wrote:I think it would be a good idea to check the kill switch as the next step.
Then the connector for the RHS switch assy under the tank.

Chocolate, I think Inge is on the money here. The connector under tank could well be the culprit.

Inge K. wrote:I think it would be a good idea to check the kill switch as the next step.
Then the connector for the RHS switch assy under the tank.

Just a question, what/where is The RHS switch assy?

Cheers

Thanks, great Inge, even in german :-)

I've got a spare RHS and will clean the connector under the tank.

Cheers

Chocolate wrote:
Just a question, what/where is The RHS switch assy?

Cheers

Inge was referring to the connector for this which is #4 in the diagram.
'assy' is the technical abbreviation for assembly. Its also referred to as the switch block.

http://technik.flyingbrick.de/images/f/f9/61_lenker_rechts.pdf

Especially pay attention to picture #6.

Holister wrote:
The fact that the brake warning light has come on means the BMU has rest itself. It will only do that when the ignition/power has been cut. So it has to be a fault in the ignition switching or connectors or wiring somewher.
I have found that the kill switch can suffer in the same way.

Thank you Holister for the translation and explanation of the problem at hand and thanks to Inge for the detailed images of the RH switch assy.

i would guess that the short time or distance between occurences of this problem is due to high currents flowing thru an intermittent dirty junction such as between a spring-loaded ball and the metal trace. 

Over a short time the resistance of the junction increases due to heating and the thermal expansion causes the contacts to move and open the circuit. 

Or there is arcing at the intermittent junction that deposits carbon residue that blocks the current path.

I'll leave all that technical electron flowy stuff up to you electronics boffins Kenny but one thing I do know is that that kill switch in Inge's pdf is totally full of schicht ..... Oh! Sorry that was oxidschicht

Cheers

Last week when I was off camping my K did that. I went at the battery earth connection first off and guess what? The darn thing was loose on the battery terminal. My second shot would have been to check the  battery positive terminal.

You are experiencing total cut off when it happens so other possibility are poor connection at a fuse or ignition fault. Have you a big bunch of keys hanging off the ignition?

92KK 84WW Olaf wrote:… The darn thing was loose on the battery terminal. My second shot would have been to check the  battery positive terminal.

… poor connection at a fuse or ignition fault. Have you a big bunch of keys hanging off the ignition?

Olaf I've checked the batterie terminal connection, they are tight.
Beside that the clock would be 0.00 if it hadn't any mass.

"Holister I'll leave all that technical electron flowy stuff up to you electronics boffins Kenny but one thing I do know is that that kill switch in Inge's pdf is totally full of schicht  ..... Oh! Sorry that was oxidschicht"

Master Holister, I've cleaned the right hand switches, no oxid "shit" looked like new.

I will go on and tell you all what I did and if it helped.

Cheers

Hello!

I'm still waiting for my new ignition.

What I did:
1.) I've cleaned the the right hand switches, kill switch etc. looked like new. Same issue after 4min riding sudently now power, the break light went on. Starts again perfectly. The clock stays on, that's why I think there is no mass - problem. With a mass - problem the clock would go of. Like if I disconnect the mass - cable from the gear box.

2.) the batterie cable are tight on the batterie.

3.) I've changed fuse one. The top one for the instrument cluster. Drove 20km no issue :-)


I will go on a longer ride tomorrow, to see if that was the issue, if not I will change the ignition to new.

Could the issue be related to the fuse I replaced?
I'm not sure that I've solved the issue.

Cheers

Yes the bulb monitoring unit is supplied power thru fuse #1, along with the Instrument Cluster, the clutch and brake switches, heated grips, additional instruments or any special equipment if added.

But fuse #1 couldn't kill the engine.

Both the Ignition Control Unit and the Fuel Injection Relay coil, along with fuse#1, get power thru the ignition switch ON/ kill switch RUN path.  Maybe cleaning of the switch has solved it for you.

The clock is powered thru fuse #3, which has power all the time regardless of ignition switch key position.

But does fuse 1 include fuel pump...?

92KK 84WW Olaf wrote:But does fuse 1 include fuel pump...?

Yes!

Thanks guys!

we will see if the issue is solved.
I presume the ignition has to be changed/repaired too.

I'll keep you up to date

Cheers

Which means the immediate cut out if the fuse is loose...

Similar to an incident last year in a dark country place came out and almost zilch from the bike. Quick investigation using light from phone revealed nothing but I remembered the forum advice about a Fuse 1 issue. Spare fuse on hand solved it. I could not see a fail on the fuse but fuse change worked. Now I pull and refit the fuses every time I do a deep clean and seems to work ok.

The fuses are kind of known to be occasional suspects due to possible poor electrical contact from moisture/corrosion. As an aside its worth when you insert a fuse to make sure BOTH sides are meeting resistance as you push it in, if not one side may end up with poor electrical contact.

92KK 84WW Olaf wrote:But does fuse 1 include fuel pump...?

No, fuel pump is powered thru fuse #6 which is fed from the FI Relay contacts, i.e. when the FI relay coil is energized and the contacts are closed.  Look at Bert's image above and you will see this.

In Bert's image the power source into the fuse is coming in from the left side, and the loads serviced are on the right side.  On the bike, when looking at the fuses thru the plastic cover, it is just the opposite--supply on right and loads on the left.

That's how you can run the fuel pump to drain the tank--place a jumper from the right slot of fuse 4 to the left slot of fuse 6.

I've had a similar problem on my Cobas replica and after changing every plug in component outside the loom, it turned out to be a broken wire inside the ignition/injection sub loom itself.
I changed it and all is well again-worth a look!

Good luck.

Thanks guys!

@Olaf could just be a simple think, I will see tomorrow, on a longer tour.

@Mike, thanks for adding, I'm getting a new ignition with cable, I will change if necessary.

Will see, time on the bike will tell :-)

Cheers

Issue seams to be solved by changing fuse 1

Since then I didn't have any drop out.
I'm not 100% sure that just replacing a fuse solved the problem, but why not.
It could also be a cable that moved in the right position.

Now all cable connections under the tank are cleaned :-)

Thanks all for the help
Cheers

The fuse box is a little expose to the elements especially if there is no cover so the contacts can fail due to oxidschicht.
Often its just something simple.. Glad to hear you're back on the road

Thanks Holister!
Weather is perfect, not to hot or to cold,
perfect to ride.

Cheers