In the Service Bulletins link that K-BIKE (thanks!) found for us, there is a mention of a kit by BMW that will fix the problem for the later K Series (solid state as opposed to relay I believe).

Does any electrical guru out there know if this should work on our older K's?

What is the date on the bulletin and I may be able to find it.

I have been thinking of this idea for myself. Going to start using solid state relays for lighting upgrade, power distribution ect as suggested by (Bert 1.0) I was thinking THIS relay $$$ as a possible unit. I have bought components from RS ONLINE before. They are fast on delivery. Even I get stuff next day out here. They can be a lil exy but!!

Looks like a ordinary relay, with some mods on the coil circuit.
Maybe to prevent that the relay kicks in, if voltage gets below a predetermined value.

Service bulletin.

Inge K.

Inge has the link to it...and yep, it looks like an ordinary relay. Oh well.

Thanks anyway.

http://jaycar.com.au/ShowLargephoto.asp?id=10476&PRODNAME=Automotive Relay 150A SPDT&IMAGE=



nice and cheep ...but ...some changes required to fit

The Jaycar relay is a bare relay and does not have the additional circuitry the Siemens (BMW) one has. I am not an enthusiast of fully solid state relays as they have a forward voltage drop due to the presence of a semiconductor and can have a steady leakage current even whilst off. If relay welding is a concern then the BMW kit or an equivalent could be a solution.

With the new BMW relay I suspect they have fitted a circuit which acts as a solid state switch for the starter relay coil to prevent the low voltage failing to hold the contacts closed. I also suspect the relay coil is wound for say 6 to 8 volts and supplied through the solid state circuit with enough volts to keep it engaged even with a low battery.

If we look at what is happening on our bikes when we push the starter button the starter relay coil effectively receives current via the starter switch and a whole bunch of connections, if the voltage is too low the relay will not pull in because the voltage required to pull in a relay is higher than the voltage required to keep it closed (called its hold in voltage). At that point we push the button and nothing happens, if there is enough voltage to pull in the relay then the following takes place.

With a weak battery there can be just enough voltage to pull the starter relay in, it pulls in and the relay contacts close with a spark at the moment of contact, at that point voltage starts to flow into the starter motor.

The current draw of the starter is huge and as a result the voltage supplied by the battery can sag down below the hold in voltage of the starter relay so the armature of the starter relay starts to release from the coil thereby weakening the spring pressure holding the relay contacts closed until the relay contacts separate and an arc forms momentarily between the relay contacts and then extinguishes. At that point current to the starter motor stops and the battery voltage rises up to the point where the relay pulls in again and the cycle recommences. The high speed pulsing or chattering of the relay and the sparking at the contacts allows them to weld shut at the point when there is sufficient molten relay contact material present when they close and the arc stops. At that precise point as the contact is closed the molten metal freezes and the relay contacts are welded closed and as a result the starter is now permanently running until the battery goes flat.

Now our bikes are similar to a car 1000 cc plus a battery and starter button why doesn't this happen to cars as often as it happens to us? I believe there are a couple of points which are a problem we have, small batteries 30 Ah or so at best plus our wiring plugs and sockets, starter switch etc. gets more damp and dirt than the average car AND when they designed the starter relay the design of the relay coil needs slightly too high a voltage to stay pulled in. I have not heard of this being a problem on say early Goldwings which are very similar in that they have 1000cc motors an electric starter and a similar battery size however I have not heard about relay welding being a problem.

What can we do, shell out for the improved relay or perhaps go through the whole starter circuit cleaning and treating every contact, switch and connection with DeoxIT so as to get the highest voltage to the relay coil. If you can keep the battery on a battery maintainer like the CTEK and keep all the connections etc in new condition I do not believe the problem will come back. However a project would be to source a starter relay with a lower hold in voltage than ours with an equal or higher contact rating.
Regards,
K-BIKE

in addition to all that .....we could help our selves out by replacing that weak link of piddly wire between the earth of the battery and the frame and the lug that its attached to .

this deployment of under sized cable and lug and dissimilar metals where it attaches to the frame is an inbuilt time bomb , just waiting for a little corrosion to raise the voltage drop across the earth link to the battery and create that voltage drop required to do the relay welding .

as k-bike suggests, cars as being not so different to our bikes ...i believe most cars have what could be called an effective earth cable of some millimeters of crossectional copper conductor and a huge lug that makes the earth connection with a minimum of 6mm bolt (more like 8mm and more in most cases ) and usually passes through to the engine propper for a second connection point.

when next your playing round under the hood of the car , check it out .

food for thought .



i

Food for thought indeed regarding effective earths, it is noteworthy that BMW did put on a larger earth cable in later versions of the K but there is no such thing as too big an earth cable and nothing to stop running a separate earth cable from the battery negative all the way up to the big frame earth lug under the tank. For any earth cable unless you go to a purpose built replacement simply doubling up the existing one is effective.
Regards,
K-BIKE

aye ! a good plan that ...and exactly what i have done ..the day i put my headlamp relay mods on. a nice big 4mm diameter copper cable .

BUT just for the sake of it ..i undid my main earth and cleaned up the alumunium (sorry usa folks, thats how we spell it out here ) to earth lug termination , under that bolt ,and did it again just yesturday .

i did notice some pitting had started into the brass lug ...and that was only 8 months since my last clean up .

i think i will be making it a yearly maintenance must do ..

just thought to go a little further today ....look at what i found











always pays to--- check--- check--- check

in this process i must admit that i found the cable for the earth of moderate size ....quite deceptive on the insulation ..i would guess at 4.5 mm diameter copper



the fix

Excellent catch there Charlie99 I would hazard a guess there are many more of those out there hiding on our bikes. That is an even better reason to remove every termination and DeoxIT them, plus it is worth putting a dollop of DeoxIT on the wire end poking out of the crimp. The other worthwhile thing after that is slipping a length of adhesive lined heat shrink over the lug and have it covering the wire over the first 10 to 15 mm of cable beyond the crimp too. Shrink it down with a hot air gun and then trim up the heat shrink on the lug so it does not get in the way of the nut when it is screwed down.
Regards,
K-BIKE

on it k-bike ....

There have been a few modifications regarding the grounding over the years. One was an earth cable from the righthand grip to the ground point, as it was noted there was an ground running over the throttle cable. Then there was a wire being fitted between the ground points on the gearbox and the main one underneath the frame. There might be more (noted a bike with an ground cable from the tripple clamps the other day).
As said before (and the above is a good show of lateral thinking) you need to check/review/clean the whole ground path on these bikes. I have seen issues with the cooling water stub not making proper contact on the engine.. Another way would be to run a ground cable from the sensor to the main ground.

ReneZ wrote:One was an earth cable from the righthand grip to the ground point, as it was noted there was an ground running over the throttle cable.

The reason for adding this cable was some issues that the brake switch had shorted, and the short being
grounded via the throttle cable........with the posibillity to jam the throttle cable.

Service bulletin.



It could be that it also been issues like this with the heated grips as well, cause I remember that an
additional ground wire was added to the set (but nothing mentioned in the mounting instructions).
Or they was thinking ahead, with the brake light switch issue in mind.

Inge K.

My solution to the wimpy BMW grounding wire was to replace the OEM cable with a universal Starter-to-Switch cable for a car.



This cable is 4GA (21 mm2) and significantly beefier than the original. I'm not a fan of using dual wire runs for a couple reasons (this is just my opinion).

High current travels on the surface of a cable, not in the core. The number and size of conductors in a multistrand cable are of greater significance in determining wire inductance than does the square area of the cable. I believe that the surface area of a dual cable configuration using normal multistrand wire is less than a single cable configuration using purpose designed cable of equivalent diameter.

Second, every connection has the potential for failure. The connector on the store bought cable is fully sealed and machine crimped meaning that the connection is air tight and not prone to corrosion as would be a hand-crimped connection.

The challenge was the accommodating the holes provided in the Starter cable; they was excessively large. I used brass washers to ensure that the bolt exerted pressure over the lug surface.

yes your right rob ..the big cable is certainly good practice ...

my only problem is the dissimilar metals . having a tinned brass lug is good ,,,having brass to aluminium is somewhat an issue for me .

i remember pulling 2 large conductors per phase of aluminium cable to supply a largish recreational club ...about 600 amps per phase worth or 415 volt stuff ....we were refused connection untill we had silvered (laminated silver ) onto the bussbars of the switchboard ...made of 6 inch by 1/2 inch copper . the silvering process stabilised the dissimilar metals between the aluminium crimp connecters ( to 20 ton presure ) and the copper , along with a liberal splash of a stabilizing and air gap removing conductive paste.

after taking off my brass earth lug evidence of electrolitic pitting was quite evident after only a few months ...a bonding compound would have helped the whole thing , the lug at one time may have been tinned but certainly not now ...

rf (radio waves) travel along the surface of copper conductors inherintly (something about corona effect )...anything below about 1mhz uses all the copper throughout the conductor ...evidence of this is to be had when looking at the manufacture of tv antenna cables (many mhz 200 and up )...where it is common practice these days to copper clad steel conductors to save costs ...it is still a requirement by superior installations that anything under video base band (5 mhz ) be made of real copper conductors as "cladding" affects velocity propogation and is quite critical whenever "teminated " transmission lines is a factor (read high security video conductors and more )

the point of having twisted multi conductor cables is to raise the effective surface area of the cable to allow cooling effect caused by loses within the length of cable this effect allows one to overrate (current and heat dispersion ) a conductor for a particular load . just convieniently it makes a good flexible cable as well if the individual conductors are small enough . solid copper tends to fail from mechanical vibration .

my point of using a second run to the earth point under tank i think is valid, the losses through several steel to aluminium junctions along the frame to engine interfaces means that the path travelled by the electricity will be of least resistance along my duplication and i would suggest that for all the lighting and electronics earth reference points originate from there . i have noted a slight rise in voltage (whilst under load) to critical eqiuipment after doing this.

but after finding the cracked lug at the battery, anythings possible

i just want make sure that the altenator has as low a resistance path to the battery as possible ...the battery is the stabilizing factor after all.

i dont want to see any surges or voltage drops if at all possible getting to my old and grey electric trickery boxes and by bonding those under tank connections to the battery i recon i have a better chance than most .

Have been following this up as there was a thread a while back with some photos of the inside of the relay http://k100rt.aforumfree.com/t2011-help-removing-the-fairing-a-starter-relay-question
So I took a look in the Bosch relay manual and found the following words to describe the starter relay operation.This shows the smaller contact is supposed to make first and break last. This raises the question when it welds which contact is it that welds and is the alignment of the contacts in the relay correct, should we be checking our relay internals?

Regards,
K-BIKE

Method of operation of leading contact

1. Closure of leading contact


Coil energized; current flows in leading contact for a fraction of a second.


2. Closure of main contact


Coil energized; current flows in main contact. The characteristics of the


tungsten leading contact make it ideal for the considerable loads resulting from


the separation arc when contacts are opening (inductive loads). The main contact ensures efficient current flow with minimum voltage losses. The tungsten leading contact (late-opening when


the contacts open) ensures that the main contacts are not subject to separation arcs.

Euro Moto Electrics sell a neat kit of cables to beef up the earth and supply lines http://www.euromotoelectrics.com/product_p/bck-577-fslash-1317.htm

Not unreasonably priced at $22.95 for a pre made kit.
Regards,
K-BIKE

good find k

i love their wording "ampacity" ....down in the text ...

Moto-bins or Motorworks also have a similar set, but I think that was only with the positive wires.

link

Inge K.

just rememberered i found this stuff on a cheap desk at one of the accessorary places earlier this year .

ill fit the right size crimp connector and see what happens

Good find there! With copper cable that does not have tinned strands it is more important than ever to give it a dose of DeoxIT D5 and then some S5 once it is all made up.
Regards,
K-BIKE

i think ill end up using glue lined heat shrink k

the crimps of that size are blind as you can see in the second pic , they have installed standard h/s but i recom the double wall glue lined will be overall much better .

thanks rob for the reminder of big cable .

Give the cables and the crimp socket a spray with D5 and then when dry with S5 then crimp them up with the correct size crimper and as you say put the adhesive sleeve over the top. That way they will just about last forever .
Regards,
K-BIKE