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R90/6 electrical question

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cbclemmens
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Re: R90/6 electrical question

Post by cbclemmens »

SW in electrical wiring diagrams is usually black (German word for black is swartz).
Craig

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schrader7032
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Re: R90/6 electrical question

Post by schrader7032 »

cbclemmens wrote:
Wed May 04, 2022 3:31 pm
SW in electrical wiring diagrams is usually black (German word for black is swartz).
FYI it's Schwartz.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

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srankin
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Re: R90/6 electrical question

Post by srankin »

How about a picture of and picture of the location of this wire? St.
Owner of a 84, R80RT and 78, R100RS

wbmoore
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Re: R90/6 electrical question

Post by wbmoore »

St. You asked for it…here ya go.
563B471C-E634-43D5-A1EF-28BD1580AD4E.jpeg
94872F56-F527-4E6E-8083-57A3757E343D.jpeg
The two black wires are tagged “B”and “X”. “X” is the wire in question. It starts at terminal 87 on the starter relay and ends at the infamous “50” in the headlight shell. They both come out of the main harness. Thanks to one and all for helping with my puzzle 🧩
Brad Moore
1960 R69; 1975 Norton MKIII; 1976 R90/6; 1992 K75S; 2000 Hayabusa
Big Bar, Northern California

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srankin
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Re: R90/6 electrical question

Post by srankin »

Man, I have to admit this is a puzzle and I am darned if I can figure out where it is supposed to go. LOL, you don't have an electronic tachometer so it sure is not for that, even if it was, on a /6, there would be a big plug into the back of the instrument cluster and the black wire for a tachometer connection would I assume be part of that block. That particular wiring harness if I recall is all one piece, The black wire would be part of the big plug, and wrapped in the tubing for the instruments.

Now if you have removed the stock instrument housing and moved everything to the headlight shell, Is the wire perhaps something to do with that particular harness? Perhaps BMW added the wire on a certain production run in advance of the switch to electronic tachometers for the up coming /7 series? I am bummed my friend is on vacation and his shop is closed so I don't have access to some of the better wiring diagrams he has on hand, mine just don't shed any light.

In the one picture outside of the headlight shell and near the coils would lead me to believe the wire goes to a coil if it has the proper connector. So as Snowbum lists, that could be a tachometer wire.

So, let me ask again, does the bike run? Does the lights, and all systems work? If so, obviously this particular wire may not be needed for your set up and is just there now to drive us all crazy trying to figure out what it was for.

It has been a long time since I peered into a /6 headlight shell, and that was I am afraid a R90S bike. I just don't remember any black wires, in the mix. Everything was color matched and had a place. St.
Owner of a 84, R80RT and 78, R100RS

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wa1nca
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Re: R90/6 electrical question

Post by wa1nca »

Found this on Vech's website
Go to Vechs Tech advice
Tech articles
Terminal markings on all German machines

#50 terminal from the heater plug starting switch (50A) to the starter

#50 terminal from the starting push button to the magnetic switch coil + in starter

#50 terminal from the starting changeover switch to the magnetic switch coil + in starter (for 12/24-volt systems with one starter)

#50 terminal from the starting change over switch to the magnetic switch coil + in starter I (for 12/24-volt systems with 2 24-volt starters in parallel)

This one ?
#50 terminal from the starting push button to the magnetic switch coil + in starter

Tommy
Tommy Byrnes
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA

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srankin
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Re: R90/6 electrical question

Post by srankin »

Very good information Tommy, thanks for looking it up and sharing. It certainly helps and jives with Snowbum's writings.

So back to my question, does the bike run, lights work as they should, is the wire needed now? This is a conversion from a /6 system of headlight, tach/speedo, ignition switch to a /5 system. Seems to me the /5 system might just be a bit simpler to wire and so this black wire is no longer needed as it would have been for a /6 system. St,
Owner of a 84, R80RT and 78, R100RS

wbmoore
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Re: R90/6 electrical question

Post by wbmoore »

Tommy…Thanks. Good information. I still don’t understand where the wire ends on the wiring diagram. I must admit ignorance when it comes to these relays.
St. Bike does not run. I want to finish the wiring. Then hot it up and troubleshoot from there. I was hoping to find out if any /6 owners knew what/where the “50” was inside the headlight shell.
Thanks to all.
Brad Moore
1960 R69; 1975 Norton MKIII; 1976 R90/6; 1992 K75S; 2000 Hayabusa
Big Bar, Northern California

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schrader7032
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Re: R90/6 electrical question

Post by schrader7032 »

Try sending a message to Snowbum through his website. On his home page, not the technical list, there is an email link at the bottom of the page. If you find something out, let us know!
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

wbmoore
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Re: R90/6 electrical question

Post by wbmoore »

Kurt….👍
Brad Moore
1960 R69; 1975 Norton MKIII; 1976 R90/6; 1992 K75S; 2000 Hayabusa
Big Bar, Northern California

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