Hi guys. So I have some electrical trolls giving me a hard time. It started with that the bike died every now and then, and the instrument cluster turned off. If I had speed it usually fired right back up, or started again by the starter. 

Today the bike died completely and it was hard to get started. I get everything from starter clicks, 1 second starts and a starter motor that does not want to stop. 

It's a 1985 K100 RT. 
BEP 3.0 fitted. 
Aftermarket gauge. 

So far I have:
Cleaned all major grounds.
Charged battery.
Taken starter apart for cleaning.
Wiggling and spraying the ignition lock with wd40. 

I'll try to upload a video. 

Thankful for any thoughts.

The starter motor which does not stop is a classical on those machines. It is due to you trying to start with a weak battery. It is the principle of the electrical welding: reduce the voltage implies increasing the itensity (the motor keeps the same need of power). The starter motor relay contacts then weld together and... the only way to stop the starter motor is to disconnect the battery.

You can try to repair that relay (it can be opened) but it is wiser to replace it by a reliable one.

The engine stopping and restarting easily with the dashboard turning off is another story. Has your clock returned to zero during the operation, which would imply a general power cut?

Poupy. The battery should not be low since its almost new and newly charged. There is a good punch to the starter as well. But it's not impossible that the battery has some fault, it has been sitting a while without being used. 

As you can see in the video, the starter sometines only runs for a second. 
9/10 times the engine does not want to fire, even trying to do a rolling start.  It's been getting worse gradually and now it is really hard to get it started. 
The starter get stuck in the end and I managed to get it to stop by hitting the starter buttons a few times. 

I'm thinking the probleme might be in the starter switch?

Get the battery checked out. There are places that will do a free battery check but charge it first. I've had a new battery fail on it's first trip, it lasted 200 Km's of a 400 K trip. I had to push start it and I managed to get it replaced
when I reached my destination.
Regards Martin.

Check the connector for the fuel pump/fuel level sender.

Put your ear to the left middle of the tank when attempting to start.  When the starter motor turns the engine you should hear the fuel pump whirring.

Get a new fuel pump, my bike used to die then would restart. I had the tank internals replaced. I needed a new rubber and gauze filter and the plastic clip, I also fitted a new fuel pump. Now the bike starts faster and runs more smoothly.

Stumpy wrote:Get a new fuel pump, my bike used to die then would restart. I had the tank internals replaced. I needed a new rubber and gauze filter and the plastic clip, I also fitted a new fuel pump. Now the bike starts faster and runs more smoothly.

Did your bike loose electrical power/instruments simultaneously? I don't see how a bad fuel pump would turn off the electrical but maybe it's connected in some way. 

Thanks

Kalle wrote:

Stumpy wrote:Get a new fuel pump, my bike used to die then would restart. I had the tank internals replaced. I needed a new rubber and gauze filter and the plastic clip, I also fitted a new fuel pump. Now the bike starts faster and runs more smoothly.

Did your bike loose electrical power/instruments simultaneously? I don't see how a bad fuel pump would turn off the electrical but maybe it's connected in some way. 

Thanks

I had another problem that stopped my electrics to shut off, the wiring to the instruments was not fitted properly. I refitted the wires and then everything worked normally. My bike is still standard, yours has been modified, recheck the wiring.

You can run a K bike without the instrument cluster connected. (As long as your clutch switch works and you pull in the clutch when starting.)  Aside from sending power to the start button when in neutral, all the instrument cluster does is monitor things.

(The only other electrical thing it does is the auto turn signal cancel.)

Stumpy wrote:

Kalle wrote:

Stumpy wrote:Get a new fuel pump, my bike used to die then would restart. I had the tank internals replaced. I needed a new rubber and gauze filter and the plastic clip, I also fitted a new fuel pump. Now the bike starts faster and runs more smoothly.

Did your bike loose electrical power/instruments simultaneously? I don't see how a bad fuel pump would turn off the electrical but maybe it's connected in some way. 

Thanks

I had another problem that stopped my electrics to shut off, the wiring to the instruments was not fitted properly. I refitted the wires and then everything worked normally. My bike is still standard, yours has been modified, recheck the wiring.

Gonna recheck this! Thank you

duck wrote:You can run a K bike without the instrument cluster connected. (As long as your clutch switch works and you pull in the clutch when starting.)  Aside from sending power to the start button when in neutral, all the instrument cluster does is monitor things.

(The only other electrical thing it does is the auto turn signal cancel.)

Thanks! What is the symptoms of a faulty clutch switch? Not even trying to start I would guess?

Update:

- Tried with a different battery. No success.
- Took the starter relay apart after the starter was racing. It looked fine, so maybe the "weld" released while taking it apart.
- Took apart and cleaned the fuel tank wiring.
- Confirmed running fuel pump while pushing starter button.
- Cleaned starter switch button.

Thoughts:

So basically there is 2 problems.

1. The starter does not function properly. Sometimes it runs for 1 second, sometimes for longer and sometimes it get stuck. Sometimes it just clicks. - Could this be the relay acting up? I´m always suspecting a bad ground when a starter is acting like this, but I have cleaned and made sure the wiring is good.

2. When the starter on occasion does run properly. The bike does not start anyway. It always started easily before so this is confusing.

How is the Engine control box connected into all of this. Could it be a faulty link?

Thanks guys

Kalle

Unplug and reconnect:

1 - Ignition Control Unit(ICU) - small black box under the very front of the tank.

2 - L-Jetronic - Fuel injection control unit under the seat.

duck wrote:Unplug and reconnect:

1 - Ignition Control Unit(ICU) - small black box under the very front of the tank.

2 - L-Jetronic - Fuel injection control unit under the seat.

Did this to both without success.

Update of the day:

- Took litterally every connector and relay apart and reconnected. After doing this the bike actually fired right up, but then went back to it´s grumpy condition with a clicking starter.

- After some more fiddling I got it started, turned it off and restarted a few times. Then it went back to being grumpy. And I got the starter relay to weld up a few times too, even though using a massive car battery thats fully charged.

- I opened the starter relay box, to watch the relay operate. It always reacts to the starter button being pushed, but usually just for a fraction of a second. The fuel pump runs when I hit the starter button.

These are my main questions right now:

- When the starter relay welds up and the starter is racing, Why is the bike not starting?
- Is the fuel pump supposed to run when I turn the ignition key on, or only when pushing the starter button?
- Could the starter relay actually be the problem? Or the signal to it?

On K75s/K100s the fuel pump only runs when the engine is turning.

Just something to try but pull the clutch in when trying to start.  The start button gets its power from either the cluster when the bike is in neutral OR when the clutch is pulled in. If for some reason you're getting flaky power from the cluster then pulling the clutch in will bypass that.

Is the engine turning when the starter spins?  If not then the starter sprag in the bellhousing may be gunked up and not engaging.

duck wrote:On K75s/K100s the fuel pump only runs when the engine is turning.

Just something to try but pull the clutch in when trying to start.  The start button gets its power from either the cluster when the bike is in neutral OR when the clutch is pulled in. If for some reason you're getting flaky power from the cluster then pulling the clutch in will bypass that.

Is the engine turning when the started spins?  If not then the starter sprag in the bellhousing may be gunked up and not engaging.

I did try using the clutch. However I have not confirmed that the clutch switch is actually working. 

How about a sidestand swith, is there one on the k100? I can not find one

No side stand switch on the 2V K100.

duck wrote:No side stand switch on the 2V K100.

Ok! 

I think I need to go back to the basics. What could cause the bike to completely loose electrical while running. This was the origin of the problem. Maybe I should take the starter motor off once again.

This is a great resource for K100 troubleshooting:
http://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm

You replugged every connector and relay,  then the bike started, then your problem returned. Do this again,  plus clean them, replug a few times. Maybe the voltage drop from the old rusty connections is the cause of the starer jamming.

Hopefully it's that simple.

SOLVED!

Basically took everything apart again + a connector to the ignition module I did not see before and also took the ignition switch apart.

It´s been starting just fine ever since.

Thank you everyone for the help provided!