Hello, I apologize if this is something that has already been solved and I either haven't found it or didn't understand the solution, but i have an 86 K100RT that had an overheated starter, the previous owner rerouted the wire somewhere else he said and left the motor disconnected. When I bought the bike the first thing I did was get a new starter motor from EME along with a new relay and battery, I have a wire going from what I think is pin 87 to the little piece on top of the motor, I plugged in the stock plug into pins 85 and 86 and I'm not sure where pin 30 goes, and I've left it empty. when I press the starter button I can hear the fuel pump priming and the relay clicking although the starter doesn't move. I don't know much, if anything about wiring or electronics so I apologize if I end up not understanding an answer, the bike is in a little bit of a rough shape although it does start if it gets towed fast enough, I don't know if that's important but I feel like it might help. 

(The photo of the relay is just so you can see what pins I'm talking about, because I'm going off the photo and I don't know if its accurate)
(I also don't know how to make them smaller)
The cable that's sticking out in the photo of the relay (with the naked red wires) is the cable that used to be on pin 87, the wire on pin 87 now runs just from there too the starter.

Before doing this DISCONNECT at least the ground for the battery.

The wire that attaches to 30 connects directly to the battery without any fuse so you need to make sure that it doesn't short to anything while you're fiddling around in the relay box. Hence why you don't want the battery hooked up.

You should find a fairly thick red wire in the relay box with a ring terminal.  That provides power to the starter relay.

duck wrote:Before doing this DISCONNECT at least the ground for the battery.

The wire that attaches to 30 connects directly to the battery without any fuse so you need to make sure that it doesn't short to anything while you're fiddling around in the relay box. Hence why you don't want the battery hooked up.

You should find a fairly thick red wire in the relay box with a ring terminal.  That provides power to the starter relay.

So the power to the relay goes into 87? And 30 goes directly to the ground of the battery?
I only ask because the red wire that I think you’re talking about is that naked red wire in the second photo, although I don’t know where to connect it to the starter. And I’ve also been wondering for a while what pin 30 did.

Marcq wrote:.....

So the power to the relay goes into 87? And 30 goes directly to the ground of the battery?
I only ask because the red wire that I think you’re talking about is that naked red wire in the second photo, although I don’t know where to connect it to the starter. And I’ve also been wondering for a while what pin 30 did.

NO!!
You don't need to worry about the battery earth (neg terminal)
As Duck said, #30 connects directly to the battery for power... with the red wire (from the positive battery terminal)
#37 feeds directly to the terminal on the starter motor. The starter motor earths through its casing via the two bolts to the gearbox casing which completes the circuit back to the battery via negative terminal. The start motor is the load.

The relay will have pin numbers imprinted next to each pin.
#85 and #86 are for the control coil of the relay which pulls the contacts closed. You should hear it click when you press the start button

It looks like you have removed the battery, that is good because there is no fuse in the wire from it to the start relay. 

In the first photo there is a terminal on what looks like a heavy wire and some black insulation hanging off of it.  If this wire is red, the terminal should go on the start relay terminal 30. 

The 87 terminal has a wire that goes to a stud on the starter motor.  With those wires connected and the battery installed, pressing the start button SHOULD make the starter run. 

Be very careful and take your time making the connections.  There is the possibility of a dead short from the battery positive to ground with nasty results. 

Start by connecting the wire from terminal 87 on the start relay to the stud on the starter motor.  Then connect the heavy red wire to terminal 30 on the relay.  Makes sure the ground wire from the battery is connected to the side of the transmission above the shifter. 

With these wires connected, install the battery and connect the red wire to the positive terminal on the battery.  The last connection is the ground wire to the negative terminal on the battery. 

Judging from the photos, this last connection could be a bit dicey.  I think I see some burnt wires in the photo of the starter. Make sure the key is off, then touch the ground wire to the negative terminal on the battery.  There might be a small spark, that is normal, if it is a big spark and the wire gets hot or you see or smell smoke don't connect the ground wire, there is a problem somewhere.

If there s no smoke or other problem connect the ground wire and try to start the engine by pressing the start button.  If everything is okay, the starter should turn the engine.

No one is commenting on the fact that the heavy gauge red wire which should go between the battery +ve and starter relay Pin 30 is completely toasted!  It needs to be replaced before proceeding any further.  Also, find out why it got so hot that it melted the insulation.  That is a sign of a major short circuit to ground at some time.

Also, in the second photo, why is there a ring terminal and black wire attached to one of the starter motor mounting bolts?  That is not factory.

The previous owner said that the starter motor overheated and that’s why it went bad, I did some research and I believe the motor and the wire burned was because the relay remained on while the bike was running, I have 2 replacement wires that I got new with the starter motor, if I do replace the naked burned red wire is there anywhere it needs to run?

the wire that's going from 87 to the starter motor is a new wire that I put in because I was afraid of the red one that has now come back to bite me.

The factory wiring is a 6.0 mm squared wire directly from the battery (unfused) to terminal 30 of the starter relay.

The closest AWG wire sizes are AWG 10 (5.26 mm2) or AWG 9 (6.63 mm2). I'd use AWG 9.

I would also use some beefy lugs at the ends of the wire that can handle however many amps that circuit uses. RBM probably knows how many amps that is.

A 14" long piece of AWG 10 or 9 wire should be able to handle at least 35 amps of current which is probably close to the draw for the starter motor.  That's a good reason to have an equally hefty ground wire since the electricity has to return to the battery.

robmack wrote:No one is commenting on the fact that the heavy gauge red wire which should go between the battery +ve and starter relay Pin 30 is completely toasted!  It needs to be replaced before proceeding any further.  Also, find out why it got so hot that it melted the insulation.  That is a sign of a major short circuit to ground at some time.

Also, in the second photo, why is there a ring terminal and black wire attached to one of the starter motor mounting bolts?  That is not factory.

Thats quite a common mod instead of to the lug on the gearbox. Even BMW techs were doing that one.

A few years ago I did a load test on my brick and it was about 25 Amps.

I went today to work on it and I cut off the naked red wire and bolted the rest onto the battery and relay as normal while also running just a separate wire to act as the one that I had cut off. I ran the new one from battery positive to pin 30 and a wire from 87 to the starter motor, I put the battery in and nothing turned on, I think it’s because the battery died, but if it’s because I triggered a sensor or safety thing that won’t let the bike turn on I also wouldn’t be surprised. I’ll try and charge the battery tommorw and try again.

How about go to this page, tab "Starter"?

Diagram

Check the #1 fuse in the fuse panel; if it is blown, you'll get zero response when you turn the ignition key to On.

I looked at the fuse and it was still together, I'm not sure what happened. I tried again and connected the battery and again nothing happened.
I only cut off the two ends of that red wire and ran a separate one along side the original other three.

I tried again and the bike still wont do anything, the neutral light wont turn on and the fuel pump wont prime anymore but the relay still clicks independently of the starter button, anytime the battery is connected.