I am turning my k100 into a cafe race and things are going well, but I am about to start the wiring.  I have the old harness completely removed.  I will be installing the moto gadget m unit for the blinkers, lights, speedo etc, so I just need the harness for the basic functions of the bike, alternator, starter, radiator fan etc.  The harness seems pretty confusing although I am a novice at it.  If anyone has any info on what I can eliminate or an easy way to eliminate wires and relays, I would really appreciate the help.

Are you keeping the OE switchgear, including the ignition switch & brake & clutch switches? If so it makes sense to keep the old harness. The only 'relay' you'd be losing is the bulb monitoring unit.

If you're going mediaeval, it's possible to make a loom just for the fuel injection (it actually already exists), plus a loom for the ignition.

Best thing is to get your loom on the table, and study that wiring diagram. It gets quite straightforward if you break it down into the different functions. Cup of coffee time.

chris846 wrote:Best thing is to get your loom on the table, and study that wiring diagram. It gets quite straightforward if you break it down into the different functions. Cup of coffee time.

That about sums it up. An added benefit is that you won't be a novice when you've successfully finished.

Have you seen this? Click on CC in the menu for subtitles if you need them.

chris846 wrote:Are you keeping the OE switchgear, including the ignition switch & brake & clutch switches? If so it makes sense to keep the old harness. The only 'relay' you'd be losing is the bulb monitoring unit.

If you're going mediaeval, it's possible to make a loom just for the fuel injection (it actually already exists), plus a loom for the ignition.

Best thing is to get your loom on the table, and study that wiring diagram. It gets quite straightforward if you break it down into the different functions. Cup of coffee time.

I am planning on replacing all oem controls, headlight, rearsets, speedo and use the moto gadget keyless ignition.  IT sounds like i just need the fuel injection loom?  Then I can get rid of the whole black box of wires and fuses and whatever else is in there.

Laitch wrote:

chris846 wrote:Best thing is to get your loom on the table, and study that wiring diagram. It gets quite straightforward if you break it down into the different functions. Cup of coffee time.

That about sums it up. An added benefit is that you won't be a novice when you've successfully finished.

Have you seen this? Click on CC in the menu for subtitles if you need them.

I have not seen this before  It looks like it should make things much more simple, well in theory anyway.  I hope to get it figured out without taking the bike anywhere to get it fixed.

Here y'go

These are just my own notes, my goofs, my mistakes. I'd be amazed if it were perfect, but it should help you get to grips with your loom (a man needs to get to grips with his loom).

One small thing.

The post does not mention2 or 4v engine.

MAF [air flow meter] in the air filter box on the 2 v engine if it s a2v K100......what happens to that and its wiring....?

‘Pologies, I referred to the MAF as AFM (airflow meter) It connects directly to the Jetronic loom, nothing else.

I’m in the middle of this job right now, so here’s the jetronic/fuel injection loom. Clockwise from left you’ve got connectors for AFM, temp sensor, 3 injectors (it’s a 75) TPS and ECU. The small connector in the middle is its connection to the main harness/bike. All the jetronic needs is power, a signal from the start button, and a signal from the ignition module. The fourth wire in the connector is actually an output from the temp sensor to the fan control module (the bike’ll run fine without it) the jetronic is almost a stand-alone - it sorts its own fuelling out.

Here’s the other half of things - the ignition module loom (which is part of the main harness) The module plug is at the bottom of the pic, and the Hall sensor connector sticks out of it. The connector at the top is where the Jetronic joins up (and you can see the yellow/red wire that the ignition module talks via to the jetronic) There are ten wires disappearing off to the right into the main loom. Vi/Gn (from the jetronic plug) - temp sensor output to fan module. Two Sw/Bl wires - one to fire coil 1, and a duplicate to drive the tacho. Sw/Gn and Sw/Ro are the two wires to fire coils 2 & 3. Gn/Ge is 12v from the ignition switch, via the kill switch, to operate the whole thing. Ge/Br is for the ignition module to supply ground to the FI relay, if it feels like it. And Br/Ro is the same for the starter relay coil.  Sw/Ge is the signal to the module from the starter button. Simples!

chris846 wrote:‘Pologies, I referred to the MAF as AFM (airflow meter) It connects directly to the Jetronic loom, nothing else.

Teach me to read the small print...you had mentioned it. Just flagging though that it normally has to be kept on the 2v.

Dunno what this shit is for though!

Maybe you've previously run the bike as standard. If so did the fan come on often, or ever at all? On the naked Ks there's plenty of breeze around things, and if you're stripping it even further for your cafe racer, then you might get away without a fan (dunno what the temps are like in N Dakota). I have a cafe racer K100 and the fan never comes on on that. Also, the fan never comes on on my K75, but that's because I didn't bother putting one on, based on my experience with the K100. Main thing I suppose is the climate where you are, and whether you anticipate sitting for hours in city traffic (or cutting through like a proper cafe racer should!) If you forgo the fan, then you can leave out that massive fan control module, plus a few yards of wiring. The bike will look even more stripped down too. Just a thought, it is possible.

As is evident from my ramblings above, it is possible to simplify things by eschewing some of the ignition module's control - just wire the starter relay and FI relay coils straight down to ground. Doesn't sound much, but it's surprising how much it will simplify things. You will lose the over-revving fuel cut out though (although the ignition retard at high revs will still operate). Likewise you'll also be able to mash your starter motor, if you really want to.

92KK 84WW Olaf wrote:One small thing.

The post does not mention2 or 4v engine.

MAF [air flow meter] in the air filter box on the 2 v engine if it s a2v K100......what happens to that and its wiring....?

Its the 2v as its an oldy.    I forget there is a 4v

chris846 wrote:I’m in the middle of this job right now, so here’s the jetronic/fuel injection loom. Clockwise from left you’ve got connectors for AFM, temp sensor, 3 injectors (it’s a 75) TPS and ECU. The small connector in the middle is its connection to the main harness/bike. All the jetronic needs is power, a signal from the start button, and a signal from the ignition module. The fourth wire in the connector is actually an output from the temp sensor to the fan control module (the bike’ll run fine without it) the jetronic is almost a stand-alone - it sorts its own fuelling out.

Yep.  I have the harness on the table and this was about the only thing I could figure out.  I wish it was all that simple.  Maybe it will be if I just take my time and slowly figure it out.  Actually I am just going to put the whole harness back on the bike for now as I don't have the m unit yet anyway since I just need the bike back together for a bit.