I'm installing a new high-torque starter and a new solenoid on my '75 FXE. I could use some competent advice on the wiring to make sure that I don't fry anything.

Starting at the starter solenoid:
There is a 4 gauge cable from the long solenoid post to positive battery terminal
There is a 4 gauge cable on short solenoid stud running to the starter motor.
There is one approx. 16 gauge wire running from the small post on the starter solenoid to the starter relay. Schematic shows it to be green, however it is black, so likely not the original wire.

Moving to the relay switch:
There is a black approx 16 gauge wire that was attached to the original relay that disappears into the wiring harness. I believe that to be the ignition wire and will attach it to the ‘S’ terminal on the relay.

The approx 16 gauge wire from the small terminal post on the starter solenoid will be attached to the ‘M’ terminal on the relay.

Here's where it gets a bit confusing, as based on the schematic I seem to be missing a wire. The schematic shows two connections on the long/positive battery solenoid post. The connection from the long solenoid post to the positive battery terminal is there. But it also appears that there should be a second, red wire running from the long solenoid post to relay post ‘B’, with the connection continuing from the relay post ‘B’ to the positive battery post. Do I need the additional wire from the ‘B’ terminal on the relay to the long post on the relay, which already has a 4 gauge cable running directly to the battery? I’m no electronics major, but it would seem as if the second ‘hot’ wire from the relay to the solenoid would be unnecessary, since there is already a direct ‘hot’ wire from the positive battery post to the long post on the relay. So possibly the schematic is accounting for multiple model years?

The schematic shows that I need to run a wire from the ‘B’ terminal on the relay to the positive terminal post on the battery. Am I correct in thinking that the wire from the positive terminal on the battery to the ‘B’ terminal on the relay switch need only be approx.16 gauge?

I think I’m only one wire away from having a new All B*lls hi torque starter and a new solenoid installed and ready. But until I can confirm that the wiring is correct I’m holding off making any more connections and pressing the starter button.

Thanks in advance for help with completing the wiring.

 

when I do this I re direct the relay and starter wiring - the original set up is prone to run on - meaning the starter wont stop cranking the engine and in some cases has caused a wire fire - this is the set up I use

you are also guessing the black from the harness is the key on wire - to me that is the driver for the relay S term but I am not looking at what you are

 

I bought one of those Blue Streak Relays too. Thought it was d.o.a. and replaced it. Found I was wiring it incorrectly. I'm not near my bike so I'm just off the top of my head right now and hope this helps. The two copper 4awg terminals need to be wired correctly, what I mean by that is it's not just a set of high amperage contacts. There is some internal wiring and the +Batt connection needs to go to the correct terminal. On my 81 FL I installed a lever start, replacing the solenoid that moves the starter gear in and out. When wiring the lever it used the "low amperage" stock relay in addition to a new "high amperage" relay (Blue Streak). The terminal from the "low amperage" relay passes +12vdc to one of those two 16awg terminals. This is the tricky part. Again, you have to connect it to the correct one of those two (I believe it is marked "S" in the drawing you provided) and leave the unused one alone. The 16awg terminal you use is internally wired to ground through it's coil.

Just make sure you have the relay orientated just like the drawing and it should work.

Man..... I hope I helped and didn't add to the confusion....

 

Thanks JZ for the visual layout - that is extremely helpful! Not just for me but for generations to come....

Just took a quick look and I don't see the two components in the lower left part of the picture. Do I need to add them?

 

with out a relay you don't have the snap to the solenoid but the black switch you have is a 50 amp relay and will do the job you need wiring it as stock not modded like I do

 

Thanks JZ. Both devices in the lower left corner are relay switches? I would need to add only one of them, correct?

 

no the one you have is a relay - wired differently then stock you need one of the two on the left

 

Thanks again JZ.

What kind of device is the Bosch unit?

I would add that unit to the existing relay / solenoid / starter configuration, and then would have the improved wiring setup that avoids potential run-on?

 

if you compare the original wire diagram and what I posted in the pictures and if you under stand what I do with the wiring to stop any chance of a run on you should go ahead and re do yours

if you don't get it looking at it in the photo then don't, as I wont be able to help other then the actual in the photo

 

John, I took the liberty of modifying your diagram. If I understand correctly, I need only one of the two components showing in the lower left area of your diagram? The wiring scheme could be either of the ones displayed?