Hi I am the new kid on the block, I have a 1986 K100RT which I have owned for about 5 years, the other day I went and had fitted 2 new tyres, I left the tyre joint and when I came to the first corner that I needed to indicate around when I did this the indicators both flashed once and the was that. I had this problem before a couple of years ago and was advised that it was the brushes in the starter motor...these were replaced and the problem was fixed. This time however when I got home and parked the bike and turned the kill switch off the starter motor tryed to start the bike up again, so I turned the key off, still the starter kept running. I ended up having to undo the battery cable before I burnt out the starter. I have removed the starter and checked the brushes...all ok, checked that the relay points are not welded..all ok, so I am now at the point of where do I go from here, does any one have the next step I need to take?

Kindest Regards Agent Mulder

If it does it with the key off, it must be the starter relay. If you reconnect the battery cables again does the starter spin again? just thinking after rereading your post and the fact that you used the kill switch to stop it then mayby, just mayby the starter swich is playing up and activated the starter when you killed the motor? I would disconnect the start button and reconnect the battery and see what happens. Keep us posted.

Hi robinm, thank you for your quick reply, I will try your suggestion with the kill switch on the weekend and let you know...

Hi er Agent Mulder, I would suggest stripping and cleaning the ignition switch contacts as well as kill switch contacts, and clutch switch if possible.
Had an identical problem as have many others and it seems to be caused by low voltage in the load shed relay and starter relay area. From memory there is a 12V but low current connection to the starter relay which, on mine, measured about 11.5 v with ignition switch on then gradually increased. After cleaning the ignition switch it was "normal" battery voltage straight away and no more problems.

Hi phil-mars, thank you for your advise, so you are saying that it is possible that when the ignition switch is off (being the key ignition switch?) it is actually on and that is why there is still power going to the starter, because that's what has had me stumped, with everything turned off the starter motor keeps running, I tested this with everything turned off and the starter out of the bike and pulled all the fuses I put a test light on the wire that connects to the top of the starter and the test light came on. I will check all these things on the weekend and let you know. By the way you said about a clutch switch, could you advise where this is, I have not seen this one? Thank you for your assistance...

Basically it is as per robinm's comment.
The starter motor acts as an earth for the load shed relay and if the starter relay is on it is a direct path from the battery through the relay through the starter to earth.
If the starter relay sticks on then nothing other than disconnecting the battery will stop the starter from turning.

I found once the battery and starter was disconnected the starter relay came "unstuck" on its own but that is not always the case.

First thing is to disconnect the battery and remove the tank and check the starter relay with a multimeter.

Once you have confirmed it is not stuck on then you can test it with a 12V source to make sure it works as advertised.

The clutch switch is basically on the end of the clutch lever and is the same type of switch as the brake light switch. I read one report of a high resistance switch causing exactly the same problem.

http://docs.google.com/fileview?id=0B7saljWp6sXMNjM1N2IxZjktZDE1YS00ZjU4LWFiMmUtNzllNmU1ZDI2ZDUw&hl=en&authkey=COa14_MI

No22 is the starter motor and 23 is the starter relay

The return path for the starter relay coil is also through No1 which is the ignition control unit

No4 is the ignition switch, 5 is the kill switch, 12 is the clutch switch, and 13 is the starter switch.

This will also give you an idea why it is so important to have clean connections throughout the bike.

Here is a different schematic (posted on the download page). It explains how the starter provides ground to the load shed relay.

Hi All, I have followed all the advice given and I thank you. Checked kill switch..ok, checked ignition switch..ok, checked starter relay again..ok, still the starter runs. I went back to the start...the starter. I pulled the starter apart and checked it again but this time I got some fine emery paper and cleaned the end of the armature where the brushes run on, I then re-assembled and everything is back the way it should be. I would like to thank you all again for your help and hope to be envolved with more discussions.

Regards Agent Mulder

So is it fixed?

Yes it is fixed and I have been on a 1/2hr ride and started and stopped the engine several times with no problems, fingers crossed for the future.

Thanks All...

Good one!!

hi guys i have this problem but my bike got hit with a 3 day storm, and stupid me forgot to put it in the shed. walked out to it turned the ing on and the battery was flat, and the hazzards where on.. it tryed to start but only got about 1/2 a rotation, and since then i charged the battery, connected it back up and the starter goes none stop without keys in bike, any ideas, or start at the top and work threw... cheers alex

As you tried to start the bike with a low battery, you burned the contact inside the starter relay and they stick together.
You can try to give a 'gentle' tap on the relay and the contacts may get free.
In any case, you will have to open the relay and clean it.

Now I have read that the kill switch is for emergency and the bike should always be controlled with the Key.
Just butting in.
Ajays

Good point Ajays, the kill switch is pretty low quality and working it now and again mechanically with the power off is good but I would be concerned about allowing any arcing by using it as a shut off on a regular basis. If you have it apart use DeoxIT on it.
Regards,
K-BIKE

ok thanks guys i lifted my tank n gave the relays a soft touch up. and bang works a treat.
cheers ... alex..... lol for a while there i was seeing my own eyes rolling and dollar signs flashing

Once the contacts are damaged, the relay will acts again. It could be anytime and anywhere. Imagine the panic if the relay stock again on the side of the road....
Removing the side panel, opening your tool box to get a 10mm spanner and then disconnecting the battery!
Take the time to open the relay NOW and clean it.

Bert

which relay is it ??? i smacked em all lol

I think you might have that image ingrained into your cerebral cortex, CF! Ta for sharing once again.

Hi Alex it is a mid sized black relay with the really thick wires going to it and those thick wires are screw fixed to the relay. One thick wire goes to the battery and the other thick wire goes to the starter.
Regards,
K-BIKE

ok thanks mate, i give it a clen asap, the bike is sheded at the moment due to poor weather here at the moment... thanks again
alex

I'm having the starter motor stays on without key in the ignition issue as well. Having taken them apart and cleaned them, it appears both the starter motor and the starter motor relay are in good working order.

Where to next? The key ignition switch? The starter button?

Thanks in advance...

Unplug the two wired that go to the relay from the wiring harness Red/black and Black/yellow They should be on the same small two pin plug on the starter relay.
If the problem goes there is trouble elsewhere but if it stays then the relay is the problem.
I have seen a starter relay with one contact welded together with the 2nd contact still ok so the relay still clicks and gives the appearance of working but is still connecting all the time.

Thanks RicK! That'll narrow it down!

I disconnected the relay, and no starter, so I guess it's the relay.

My relay is in much the same state as the one in post #8 this thread - i.e. the same arm is missing the point from a previous misadventure, and similarly I had bent the same arm down. On close examination it was significantly closer to contacting than the other arm. I re-bent it so that they're contacting at the same time, and when I tried the ignition the battery didn't have enough charge to close the contacts. I think the battery's stuffed, so I'm getting a fresh one to try it all out with that.

In the event that I need a new relay, RicK, I saw you'd found a cheaper version:

RicK G wrote:We have not got a crisis in Australia (that is what the government tells us so it must be right) and $65 is expensive here for one of those relays. I have priced a relay that is just as good and it was $16

Care to share?

The contacts are not meant to connect at the same time the small one contacts first and is made from a material that wont suffer much from arcing and then when arcing canr occur the second makes contact which is designed to carry high currents.
It only a matter of 1 mabe 1.2 milliseconds but that electrickery is quick stuff.

My comment, One of the most important items on our bike is the battery.
If you continue to try to start with a low battery you will get contacts weld together.
Always have a fully charged good battery.
Ajays

I too have had this total pain in a---- problem not exactly a fool proof electrical design is it. As a belt and braces issue I have fitted a battery Isolator switch to battery earth line doubles as an extra anti theft device too (removable Key). I have also made the possative battery terminal more accessable to use a booster on. This time of year the bike is left for long periods without use.
I have become paranoid about battery condition and have fitted the expensive Gel battery hopefully I will not get caught again.

Hi

Do not jump start a K with the original ABS. It is not protected against surge currents and blows - I know from doing it.

I now use a low current maintenance charger before starting my K after leaving it standing for a few weeks, so that I am always starting with a full battery.

thank you this helps me 2. cheers guys for sharing.

Hey everyone, i'm also experiencing this problem. given that ive only owned the bike a week, im not very familiar with the bike/platform but im pretty handy in the garage. 

Here's what's happening...twice in the past week the starter will not shut off. the killswitch would not make it stop the first time it happened nor would removing the key. in order to get the system to shut down i popped it into gear and released the clutch and the bike stalled and the starter finally stopped.

this happened a second time in one week so now i dont want to ride the bike until i get to the bottom of the issue. the issue has only happened twice and ive been riding the bike nearly daily in the past week.

the previous owner told me he recently replaced the battery (it looks brand new). he also provided a batter tender as well. right now i have the system charging (in hopes that its just low voltage).

in order to check/test the starter relay, i need to remove the gas tank? im guessing ill need to drain all the fuel from the tank first before removing (that sounds like a very long process). correct? 

thanks for your help!

Umichchris--it's not necessary to drain the tank to remove it.  But it is pretty heavy when full.  Make sure you have a good, soft place to set it down before taking it off the bike.  Also, be careful when removing the fuel line from the tank that heads to the fuel rail.  The pipe/barb coming from the tank is aluminum and easy to snap off when trying to wiggle the fuel hose off of it.  Unfortunately, I know this from experience.

Sounds like the starter relay - if the PO tried starting w/a weak battery it could have fried the contacts together.

Very common.

+1 that.
You can remove the cover of the relay and check out the double contacts inside. The smaller contactor probably has a small bead of molten metal bridging across. If that contact is destroyed the relay should still work with just the larger contactor but best to replace the relay as soon as you can and keep the old one as a backup. Sometimes the only way to stop the starter is to disconnect the battery. If you have to do that, best to remove the neg cable at the gear box.

Re removing tank.... depending on the year model, be prepared to stick a bung in the return spigot. Earlier tanks have don't have a non-return valve.

True about the return valve on the tank. My '85 has one. But even on later year bikes, some people remove them because of malfunction or noise.

Hey everyone, i thought that since i just bought the bike, perhaps the battery was low and needed a solid charge...that was one of the top suggestions for a fix. So.....i connected the bike to the battery tender each night after riding throughout the day for the past week. No issues.


BUT THEN...today while on my way into the office i could hear the starter continually running. In addition to that, the electronics on the bike were malfunctioning. The headlight would not turn on and my turn signals intermittently would not work either. Right now, im just planning to ride home midday and park the bike before it gets dark out.

The start would not shut off until i un-bolted the negative cable on the transmission (luckily i was prepared for that thanks to your suggestions - thanks again all).

So, now...im not sure where to start. Its definitely not a low battery issue. I can see in all of the paperwork and maintenance records from the previous owner that the starter relay was replaced back in 2014...so this may be a recurring problem...wish me luck!

A low battery will cause the starter relay contacts to weld together regardless of its age and if the starter is spinning then the load shed relay will release and stop the headlights working. Open the relay and check the relay contacts, if welded shut which they will be replace the relay and get the battery load tested and replace if it is at all in doubt.

One other thing: getting the starter relay open is not easy (but I agree that this needs to be done as it appears quite likely that this is your issue). To open it, it will have to be removed from the bike. I think I ended up having to use 3 very thin-tipped flat blade screwdrivers and a couple of razor blades as shims to pry the cover off. And, even being really careful, I still cracked the cover a little bit.  Maybe there's some trick that someone else could share that makes the opening task easier?

umichchris:

We posted on Oct. 30th that it was most likely the starter relay...

Brad-Man wrote:umichchris:

We posted on Oct. 30th that it was most likely the starter relay...

thats what ill be testing out this wknd. hopefully thats exactly the culprit!

took everything apart....gave the relay a sharp tap like suggest within this thread and others...put the bike back together and the issue came right back after a couple of starts. 

i just ordered a new relay today. hopefully it arrives this week so i can install this coming weekend. 

all connections are nice and tight. my battery is pretty new (replaced in February of this year). the voltage output reads roughly 12.89v when i put it on a tester so i dont think thats the issue.

hopefully a brand new relay will fix the problem. ill be sure to report back...

You guys actually got these open?? I have a Tyco aftermarket relay by the looks of it.. very difficult to open (I'm not having any luck, about to go at it with a screwdriver and a hammer)  My friend has a new one that has different numbers on the top but same 12V and same post set up.. will this work or could I do damage to the bike by trying it?

also my aftermarket one which I've taken off the bike has a different serial number than the original..

Found an aftermarket relay for $20AUS at a local auto parts store and fixed the issue ) Now to figure out what's draining my battery or if this new battery is just a dud..

Starter staying on: Another thing to check is that the starter button is not jammed down. Removing the screw will show the back of the starter button... pressing the green button pushes a metal pin that creates a circuit by linking two tabs. What can happen is that the pin gets stuck between the tabs. I get this a few times. 30 secs fix.

Opening relays... try butter knives or precision screw drivers. When filing the relay points that weld themselves together (low battery), I found a cheap set of lenses (Ebay / China ... $5) that attach to the mobile phone to be very useful... especially as the eye sight of your average BMW owner is sure to be fading 

Guy