Some of you may remember that i had a small fire on my k100LT a few weeks ago.  I was hoping that is was just the wires from the ignition barrel to the loom connector that had gone but alas not.

I finally got around to stripping it down last saturday and found that the damge is from the ignition barrel right through the main loom and almost up to the fuse box.

So i need to replace the main loom.

I need help on the following points please.

1.  Is the 4v loom the same as the 2v loom..mine is an 87 2v.

2.  All advice and help welcome on home to do this.  It seems like its just a unplug, replace and plug job but and i missing something?

3.  What else might have been damaged?

4.  Why didn't the fuse blow shutting off power from the battery?

Help please.

Mike

The 4v loom isnt the same, it could be modified to do the job but if at all possible get a 2v loom.
There are many wires in the main loom that arent fused because they feed to distribution points that are then fused as seperate items and if one of those live wires was burned through then where there aint no fuse it cant blow.
When I built my yacht every wire that left the control panel was fused and the only feed that was not fused was the main cable from battery to the starter via the solenoid.

RicK G wrote:The 4v loom isnt the same, it could be modified to do the job but if at all possible get a 2v loom.
There are many wires in the main loom that arent fused because they feed to distribution points that are then fused as seperate items and if one of those live wires was burned through then where there aint no fuse it cant blow.
When I built my yacht every wire that left the control panel was fused and the only feed that was not fused was the main cable from battery to the starter via the solenoid.

Thanks for the reply.

Guess i'll have to wait for a loom to appear for sale as there aren't any about at the moment.  I bought this bike to use as a winter hack and so far it's not seen any winter.

Mike

Use a 2V wiring harness.  The 4V harness is different enough that it wouldn't make sense to try to kludge one in. 

The power to/from the ignition switched is wired directly to the battery/alternator wiring and is what sends power to the switched items of the fuse block. My term for it would be "pre-fused wiring."

From the couple of burned up harnesses I've seen, when one or more circuits short they heat up the bundled wires enough that they'll burn/melt not only their own insulation but that of surrounding wires they're bundled with as well.

Mike101 wrote:

RicK G wrote:The 4v loom isnt the same, it could be modified to do the job but if at all possible get a 2v loom.
There are many wires in the main loom that arent fused because they feed to distribution points that are then fused as seperate items and if one of those live wires was burned through then where there aint no fuse it cant blow.
When I built my yacht every wire that left the control panel was fused and the only feed that was not fused was the main cable from battery to the starter via the solenoid.

Thanks for the reply.



Guess i'll have to wait for a loom to appear for sale as there aren't any about at the moment.  I bought this bike to use as a winter hack and so far it's not seen any winter.

Mike

Mike - look on the Motor Works site they seem to have stock

 

ungaas wrote:

Mike101 wrote:

RicK G wrote:The 4v loom isnt the same, it could be modified to do the job but if at all possible get a 2v loom.
There are many wires in the main loom that arent fused because they feed to distribution points that are then fused as seperate items and if one of those live wires was burned through then where there aint no fuse it cant blow.
When I built my yacht every wire that left the control panel was fused and the only feed that was not fused was the main cable from battery to the starter via the solenoid.

Thanks for the reply.



Guess i'll have to wait for a loom to appear for sale as there aren't any about at the moment.  I bought this bike to use as a winter hack and so far it's not seen any winter.

Mike

Mike - look on the Motor Works site they seem to have stock

 

I've given MW a call and they are looking for me...they don;t have many staff in at the moment so i'll have to wait until next week to get one.

Is it a mare to change...i'm not looking forward to it at all.

Iv'e not done one yet, so cannot comment,but, would think using a camera and a labelling system you'd be fine.
This site is always very helpful if you are stuck.

 

If Motorworks ain't got any in stock....it is a few on German Ebay...both with and w/o ABS.

You need to be careful with letting that albino arctic gerbil play with sparklers it may set fire to itself and I dont need to read the headlines here saying NORWEGIAN MAN FOUND EATING ROAST GERBIL.

No problem, Rick...it's burning rather slowly, and he's trained to spit.....
and light the next one......but this time of the year often is a bit hard on the whiskers.

I may well have a spare loom in the basement, not sure if I took one of the connectors off of it but can have a look and see what state it's in. 
It's from a 2v 88 K100

twincarb wrote:I may well have a spare loom in the basement, not sure if I took one of the connectors off of it but can have a look and see what state it's in. 
It's from a 2v 88 K100

Cheers...mine is a 2V 1987 K100LT non ABS.

Mike

Hi Mike - like you I found out the hard way that BMW have the best system of all to protect the fuses in the fuse box by not fusing any of the main cables. Doh!  I would accept the starter /alternator/battery cable not fused but not the rest. Yvonne at M/W came up trumps for me and between the two harnesses made a good unit. Changing the harness is a b_t_ch of a job but I suggest a digital camera, empty card and a full battery! Any wire you are to move, photograph it first, and also label it using masking tape - once over the wire and join the two tails together. Write with a sharpie what it is and where it connects to. If a joint in the wire, label both ends and mark A1 on on each end for headstock area, B1 on for under tank, C1 on for the Relay box and so on. I realise I am probably speaking to the knowledgeable but you must be methodical and careful. Label EVERYTHING before you start to remove the old harness and check each wire to make sure it has the same colours as the replacement. My 2 harnesses were for the same production year but there were six wires that were not the same colours.
One important thing - TAKE YOUR TIME. 
I reckon it took me two weeks to do the change but I had some repairs to do as well.
If I can help with any assistance do not hesitate to get in touch.
Regards

Am I missing something but it looks very straight forward to me.

Each connector seems to be almost unique with no two matching in the same part of the bike.

I have undone a few connectors under the tank but I will stop now until I get the new loom so I can compare as I go along.

Please correct me if I am wrong.

Mike

You are correct that wiring colors and unique connectors make it pretty easy to swap in a 'new' main harness.

The one exception is the common piston switch that is used for:

- clutch switch
- front brake switch
- rear brake switch (on early Ks)
- choke indicator

The one I have seen mixed up a few times is the Gear position indicator and fuel tank plug which are the same and under the right side cover. Careful checking of the colours will give you the right plugs.

some great recommendations

cheers