Last week the bike started after winter almost immediately. It started quicker than my car. 

This morning, I wheeled it out of the yard, clutch in, hit the start button and all I hear was a faint click. I tried again, nothing. Keys out, keys in and once again a faint click. I figured there was an electrical issue. So I wheeled it back into my yard, tried again just for the sake of chance, and she started. Strange. I then let the throttle off before its warmed up fully and obviously she shut off and went back to the previous state. 

Now, since checking the battery voltage (11.5), all I'm getting is the following:

About half a second of starter motor, then a few seconds of fuel pump and relays etc. 

This cycle continues for as long as i hold the start button. It's as if the starter motor is only engaging for a split second and not turning the engine over enough to fire. 

Is it the starter motor that's had it, or do I need to check elsewhere?
All I've got in terms of diagnostics are my hands and a multimeter. I've read elsewhere about checking fuel pressures etc but I wouldn't have a clue where to start. 

Thanks in advance!

Battery voltage 11.5.

Start there and recharge battery. While there could be other issues battery is first point of call. Make sure the connections are good.

If nothing happening starter brushes could be a problem, getting it out for a look is not difficult and they are not expensive or difficult to replace.

Don't be tempted to keep trying to turn it over if is sounding tired or just clicking because you could fry the starter relay.

Hello!

A K should run :-)
In your case I would charge the Batterie so it has at least 12.2 vol.
Anything between 12.2 and 13 vol. should be fine.
Even if it has 12.5 vol it could be dead, because one cell isn't working.
You could try starting with a good known batterie or start with the car batterie. To make sure it isn't the batterie.

Cheers

Get the battery fully charged.  Then  put a new one on your "to do" list.  Since it seems to have sat for a while with less than a full charge, I am afraid that it has met it's demise, and can no longer be relied on to perform as required.  It will only cause you painful inconvenience to try to carry on with it.

Another thing to check is the contacts in the key switch.  They do get dirty/worn, and can cause all sorts of electrical nuisance including random shutdowns while riding.  There seems to be a bit of that particular problem occurring of late.

The battery is fairly new supposedly, but either what when I get a battery charger I'll get it hooked up. I don't think it's the key side of things as the lights function as they should, including indicators. That's what makes me think it's something beyond a switch

Hopefully you're all right and it's just the battery playing up. I'm half tempted to pull my car round to the bike and see if I can jump it off my car with the engine running. That way it should isolate the battery issue immediately.

JaseYPK wrote:I'm half tempted to pull my car round to the bike and see if I can jump it off my car with the engine running. That way it should isolate the battery issue immediately.

I wouldn't attempt to jump the bike off a car that is running due to excess eletrickery issues that could damage your bike's ECU. The car's 12.5 or more volts from its battery should suffice.

Two Wheels Better wrote:

JaseYPK wrote:I'm half tempted to pull my car round to the bike and see if I can jump it off my car with the engine running. That way it should isolate the battery issue immediately.

I wouldn't attempt to jump the bike off a car that is running due to excess eletrickery issues that could damage your bike's ECU. The car's 12.5 or more volts from its battery should suffice.

Oh really? Thanks for the heads up! I don't want to create more problems than I may already have! Haha

A fully charged and capable battery should sit at about 12.5 to 13.1 volts, static. Since you have a voltmetre, why not connect some cables from a known good battery to your bike's questionable (11.5 static volts!) battery, re-connect the voltmetre to the bike's battery, key on, watch the voltmetre as you crank the bike over - does it drop to well under 11 volts as it cranks before firing? If it starts does it now charge at 13+ volts (minimum) from about 2,000 revs or higher with the starting battery disconnected? If it stays up in the re-charging range of 13.5 to 14.2 volts or so with a few good stabs of the throttle, it may be salvageable, and your bike's alternator may be doing its job.

I sell bike batteries. I can count on two hands in ten years how many 'supposedly new' batteries have given up the ghost in barely a few months' time. They don't always come to the retail outlet in a state of full charge. I always charge a battery fully before handing it off to a customer. The key is to regularly use a low-amp (.75 to 3 amp) charger, preferably a 'tender' of sorts, and to ride the bike regularly to keep the battery in good nick.

Two Wheels Better wrote:A fully charged and capable battery should sit at about 12.5 to 13.1 volts, static. Since you have a voltmetre, why not connect some cables from a known good battery to your bike's questionable (11.5 static volts!) battery, re-connect the voltmetre to the bike's battery, key on, watch the voltmetre as you crank the bike over - does it drop to well under 11 volts as it cranks before firing? If it starts does it now charge at 13+ volts (minimum) from about 2,000 revs or higher with the starting battery disconnected? If it stays up in the re-charging range of 13.5 to 14.2 volts or so with a few good stabs of the throttle, it may be salvageable, and your bike's alternator may be doing its job.

I sell bike batteries. I can count on two hands in ten years how many 'supposedly new' batteries have given up the ghost in barely a few months' time. They don't always come to the retail outlet in a state of full charge. I always charge a battery fully before handing it off to a customer. The key is to regularly use a low-amp (.75 to 3 amp) charger, preferably a 'tender' of sorts, and to ride the bike regularly to keep the battery in good nick.

Sounds like some good advice, thank you. 
If the weather holds out tomorrow I'll get my car battery hooked up to the bike with the multimeter inline and see what the readings are. In a way I hope it's a simple fix like a new battery, but on the other hand I don't want to shell out for a new battery! 

Hopefully tomorrow I'll have some answers!

Hi

One word of advice.. Replace the battery with a known good one.

I hooked up the multimeter to the battery to do that little test. 

Starting voltage was 11.7V

When cranking it dropped to between 6-8V for the initial blip of the starter trying to turn. 

I haven't been able to get my good battery from the car round to my bike, but tonight I'm gonna get that battery on charge!

What should the voltage drop to on cranking? Or is my battery just dead in the water? 

Cheers

Battery either discharged or dead but one or two other possibilities

If its dropping like it did it means your starter is trying to get the juice but don't keep doing that as its not getting enough to turn over.

Even before you put the battery in you could charge it fully and then leave it sit for 24 hours or more and see what the voltage is when charged and after 24 hours. It should be staying up as TWB said. If its gone way down to 11v, not a good sign.

I didn't check on battery type but if a lead acid type be sure the electrolyte level is correct.

My money is on the battery. If the battery shows up as good come back and let us know.

92KK 84WW Olaf wrote:Battery voltage 11.5.

Don't be tempted to keep trying to turn it over if is sounding tired or just clicking because you could fry the starter relay.

We all know about this, just passing the advice on!!

Crazy Frog wrote:DO NOT try to start the bike if the battery is low.
You may end up burning the starter relay.

Got it, thanks. How will I know of the starter relay has gone? I'm assuming just no starter kicking in? I've borrowed my dads car battery charger so I'll have my battery on charge tonight and see how it deals tomorrow!

What happens is that the contacts weld themselves together and the starter stays running and only way to stop it is disconnect the battery. The power from the battery to actually turn the starter goes through the relay and this is not switched.

You are unlikely to have done it so far because its still working. If it was stuck it would spin the starter as soon as you connect the battery.

If as you say the voltage drops to 6-8 volts at start up then the battery IS dying. Take it to an auto shop to get a discharge test which will show that it is dead and then buy a sealed AGM type which will give you a good few years. I got 7, nearly 8 years from my Motobatt. I have seen so many people stuff about with dying batteries and eventually need to get one in a hurry when it does turn up its toes that they pay a premium price because have not the time to shop around.

Hi

The Bmw k100 has a lot of electronics..your battery might have sufficient charge to turn the starter but that's all..
Sounds to me like your battery is past the point of no return, even for a recharge. Those voltage readings suggest to me it's time to replace your battery...with a proper motorcycle battery...don't know about starting bikes with a car battery.
Our bikes require a certain amount of voltage for the bike to start. The starter motor turning doesn't necessarily mean there is sufficient voltage for the bike's electronics to function correctly.
Before delving into the more complex tests and uneccessarily replacing parts, I suggest you replace your battery.
I was having all sorts of issues trying to get my bike to start...starter motor turned, engine backfiring, etc.
I replaced the battery with a known good one and the bike started...
Good luck.....

Cheers
Gabriel

I recall reading that if the voltage is below 9volts then the ECU wont work. I think this was refering to the K100 but may have been one of the BMW cars I have owned but it is a common thing to have that in an ECU.

I was researching relays for a friend around another subject and came upon an interesting unit that could be used to replace the generally expensive and unreliable OEM starter relay.

Problem: When the battery has a low charge, attempting to start the bike could result in a damaged starter relay, with the consequence that the engine will continue to turn over until the battery is drained or it overheats and gets damaged.  The reason is because the low battery voltage combined with the high cranking current causes the relay’s contacts to weld together.

Solution:  I found a high current (120A/12V) contactor on Aliexpress that appears very promising as a replacement for the OEM starter relay.  What is the difference between a contactor and a relay?  The starter relay in the K-bike has a single pair of contacts through which all current flows when cranking the engine.  


As shown in the image above, a contactor has two pairs of contacts through which current flows, spreading the load across four contact pads, and being less likely to heat up and weld together.  Furthermore, the actuator arm consists of a bar with the contacts at both ends.  When the contactor is turned off, both contacts break, with a more positive cut in current flow.  Contactors are commonly used in high power switching applications.

The contactor I found has a very small package – just 42mm X 42mm X 42mm in size.  There are two ¼” spade terminals for connecting the coil leads and two M6 studs for connecting the starter battery and motor leads.  The pickup voltage is 7.8V and release voltage is 1.2V.  This low pickup voltage and broad hysteresis (difference between the voltages) means the contactor is not as susceptible to oscillation as is the OEM starter relay.  The main contacts are rated at 120A and the maximum power handling capacity is 1680 W (about 2.2 HP), more than enough to handle the current drawn which cranking the engine.  The price is also very attractive at around US$12 each; cheaper in larger quantities.  

http://www.aliexpress.com/store/product/200a-starter-relay-automotive-relay-contactor-relay-12v-24v/346626_1649592976.html?spm=2114.12010108.0.78.eRhDCI



My friend will be ordering some so if he can spare one, I’ll try it out in my K75 to see how it works.

Good find Rob the stats look the goods. I am always wary of Aliexpress as I have had 4 real bad experiences there with retailers selling factory rejects then refusing refunds

Searching for part number "WM686" will turn up examples on other online venues like Ebay and Amazon. These vendors have better return policies than Alibaba, et. al. I'm sceptical at the moment until I get one of these in my hands. The marketing hype may belay the actual unit. They say contactor but maybe the insides are a standard relay, I don't know. When I get my hands on one, I'll dissect it.

Been having starter relay problems for a while and just replaced my new EME relay with an old spare I had.
Found a WM868 on AUebay for about $8 which ive just ordered. We'll see how it goes.
Thanks for the research there Robert 

I shall have a look at the gathering, I'm interested in one for the chookie.

Please snap a picture of the insides, Kaptain, when you get it. Interested to see what it looks like. The case is held on with a small lip; just pries it away.

So I guess the battery just needed a charge.... It charged to 13.4V over night, on crank it dropped to about 10V and I took her for a spin, and voltage read around 12.4 throughout the ride and now back home. 

I think I need to invest in a battery charger. Thanks for the help and advice guys, and sorry for making a song and dance over something so simple! Haha  :joker:

On the relay note, that replacement looks like a good future proofing method if it works as advertised!

That's what the forum is for.

Lots of us have encountered the same problem and its a good thread for anyone else finding the same problem.

Most Japanese bikes from the Eighties onwards use contactors for starter relays and most of those are rubber mounted. Okay, so you'd need to mount it outside (underneath?) the relay box, but it's a thought. Mmmm... might just go that route on Brick2.

What does the starter relay or connector actually do? I mean why not just have a switch (or start button) interrupting the live from the battery to the starter motor? 

Clearly I'm not an automotive engineer and there has to be a reason for having one?

JaseYPK wrote:What does the starter relay or connector actually do? I mean why not just have a switch (or start button) interrupting the live from the battery to the starter motor? 

This is an easy modification. I have a hidden 20A rocker switch on the ground.
If you shut it off when the starter relay is welded, the starter will stop.
This is also a very cheap immobilizer (Anti theft).
The only problem is that every time you shut off this switch, you have to reset the clock.

Its to do with the amount of current that the starter requires. Too much for the handlebar switch which can only accommodate a limited number of smaller cables or wires.

In simple terms when you press the starter button it then energises another much bigger switch which is the relay. Other sensors feed into this but ignore that for now. When its magnetised it immediately moves the contact plate to electrical contact with the two terminals inside the relay. [One of these is connected without a fuse to the battery live terminal, the other one goes on to the starter motor]. This then completes the connection from the battery to the starter motor [and can handle the amount of current by being thicker wires and bigger connections] immediately making the starter motor spin. On the K, once the engine speed hits I think its 710 rpm it disables the circuit to prevent the starter being damaged and the relay then goes back to the way it was cutting the electrical supply to the starter.

Relays are much less prone to arcing and other problems than the small handlebar switches.

Sorry if it sounds simplistic but its also for benefit of anyone reading the post after.

92KK 84WW Olaf wrote:Its to do with the amount of current that the starter requires. Too much for the handlebar switch which can only accommodate a limited number of smaller cables or wires.

In simple terms when you press the starter button it then energises another much bigger switch which is the relay. Other sensors feed into this but ignore that for now. When its magnetised it immediately moves the contact plate to electrical contact with the two terminals inside the relay. [One of these is connected without a fuse to the battery live terminal, the other one goes on to the starter motor]. This then completes the connection from the battery to the starter motor [and can handle the amount of current by being thicker wires and bigger connections] immediately making the starter motor spin. On the K, once the engine speed hits I think its 710 rpm it disables the circuit to prevent the starter being damaged and the relay then goes back to the way it was cutting the electrical supply to the starter.

Relays are much less prone to arcing and other problems than the small handlebar switches.

Sorry if it sounds simplistic but its also for benefit of anyone reading the post after.

That's exactly the explanation I was looking for thanks!

robmack wrote:Please snap a picture of the insides, Kaptain, when you get it.  Interested to see what it looks like.  The case is held on with a small lip; just pries it away.

it's on a slow boat from China so it may take a few weeks.

I'm going for the pukka contactor option on Brick2 because I can't help fiddling with things! I have a secondhand Kawasaki 750 Zephyr contactor on the way; a quick check tonight showed that it should be possible to mount it on the outside of the relay box in the 'recess' where the starter relay mounts on the inside of the relay box (did that make sense?). Piccies will follow.

Kaptain Holister wrote:

robmack wrote:Please snap a picture of the insides, Kaptain, when you get it.  Interested to see what it looks like.  The case is held on with a small lip; just pries it away.

it's on a slow boat from China so it may take a few weeks.

Relay arrived last week. Here's a pick of the insides. It has one hefty looking set of contacts. Also, there's no surge protection.

The oem starter relay by comparison has a pair of joined contacts. This is a pic of one of my old relays with a destroyed contact.

Looks like it dropped from 120 amp to 100 on the trip to your place nige??

The one I ordered was a 100A. Don't remember seeing any 120A on ebay at that time.
There's no surge suppression or back emf filter that you get with the latest bosch/tyco unit from EME (75A) so I'm not sure if this one will be suitable for the K starter. Tho' it would be easy enough to solder a couple of diodes across the coil terminals 85 & 86... waiting for Robert to cast his expert eye over this for comment.
Cheers

Hmmm, they advertise a contactor but that's just a relay. I'd rather preferred to have seen two contacts and a contactor bar, instead of a relay arm and single contact. And there is still a thin flexible contact arm. I think the only saving grace of this relay would be its behaviour when presented with 10V or less coil potential.  It would suffer the same fate as the OEM relay if it started to oscillate around that voltage.

Picking up this thread on the starter relay again.

First, that aftermarket "contactor" is not really a contactor; it's just a regular relay.  It has no suppression circuitry on the coil so I would highly recommend installing a snubber diode circuit across the coil before installing it in the bike.  It has the potential to kill the ICU if not so equipped.  There's already evidence that installing aftermarket starter relays in these bikes which don't have snubber circuits can harm the ICU.

An adequate snubber circuit would look like this:

Source: https://www.element14.com/community/servlet/JiveServlet/download/11344-5945/13c3311.pdf  

There was an interesting application note I read while researching snubber circuits.  It stated the following:

A typical relay will have an accelerating motion of its armature toward the unenergized rest position during drop-out.The velocity of the armature at the instant of contact opening will play a significant role in the relay's ability to avoid "tack welding" by providing adequate force to break any light welds made during the "make" of a high current resistive load (or one with a high in-rush current). It is the velocity of the armature that is most affected by coil suppression. If the suppressor provides a conducting path, thus allowing the stored energy in the relay's magnetic circuit to decay slowly, the armature motion will be retarded and the armature may even temporarily reverse direction.The reversing of direction and re-closing of the contacts (particularly when combined with inductive loads) often leads to random, intermittent "tack welding" of the contacts such that the relay may free itself if operated again or even jarred slightly.

Source: http://www.repeater-builder.com/tech-info/pdfs/relay-coil-suppression.pdf

The suppression device on the old OEM #61311459008 starter relays was simply a resistor paralleled across the coil.  This created a resonant circuit that dissipated the back EMF energy in the coil into heat when the ground was cut by the ICU, thus protecting the switching circuit in the ICU.  The resonant circuit also contributed to a slow decay in the current that exacerbated the welding of the starter relay contacts, I believe, if the above quote is true.  The OEM replacement relay by Tyco (Bosch) had a diode snubber instead of a resistor, which results in less chance that these newer designs will weld the contacts.

I'd venture to say that if the old OEM starter relays were to be modified to remove the resistor and to substitute a transient suppression device, these relays would no longer exhibit welded contacts.

robmack wrote:I'd venture to say that if the old OEM starter relays were to be modified to remove the resistor and to substitute a transient suppression device, these relays would no longer exhibit welded contacts.

That makes a lot of sense.

Dai wrote:

robmack wrote:I'd venture to say that if the old OEM starter relays were to be modified to remove the resistor and to substitute a transient suppression device, these relays would no longer exhibit welded contacts.

That makes a lot of sense.

I see your piont Rob but mostly the welded contacts we see on these relays come about because of excessive current due to low cranking speed and failing batteries.  Correct me if I am wrong but I don't see the zenner and diode would fix that.

Rick,

the diodes would dissipate the back EMF quicker (they appear as a short circuit across the coil), allowing the residual magnetism in the relay coil's core to collapse faster, and permitting the spring to mechanically snap the contacts apart more positively.  That mechanical action reduces the possibility that arcing across the contacts will be long enough to cause welding.

The resistor that's used in the OEM relay stores the back EMF energy longer (it's a resonant circuit with an associated decay), making the relay coil's core magnetized longer and not allowing the spring to snap the contacts apart as designed.  If the contacts can't release quick enough, the resulting arcing will increase the likelihood of welding them together.  I remember reading that what actually happens in the relay with a low battery condition is that the contacts bounce open/close a few times which strikes an arc and welds them together.

Hope that made sense; I'm basing it off my interpretation of the source material I referenced above.

Yes I know the basics of all that Rob but what happens is that the contacts weld together while they are closed because the current flowing is much higher that the relay was designed to carry. When the contacts are closed the back emf is nonexistent.
The overheating and welding may in part be caused because of poor contact due to previous arcing but we have seen brand new relays weld together which says to me that it is very simply because the relay is not up to the job in anything except ideal circumstances.
Pease note I am not advocating that the zenner and diode is unnecessary but that it isn't going ti fix the main cause of failure.

My new Tyco relay with diodes welded its contacts back last December. Battery was good but found starter motor needed a clean out. Been all good from then on with an old refurbed oem Bosch resistor type.

I thought the contacts welded because the spring pressure, designed to snap them back open, was challenging the coils ability to keep the contacts closed when the battery was getting down. Its cranking and trying to keep the coils working, hence keep the contacts closed. All gets a bit much and welded contacts seem to be the result. Those zenner things help with that rob?