My second airhead - R75/6

Discussion in 'Airheads' started by katit, Oct 13, 2021.

  1. nmalozzi

    nmalozzi airheaded

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    When I converted my r80rs to a "naked" bike there were no videos. I just started unscrewing/unbolting things until it wasn't on the bike anymore, lol. What I'm trying to say is: you got this!
    #21
  2. katit

    katit Been here awhile

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    I know. I try to discipline myself with this project and do only what is necessary. Thats why removing extra bolts were a chore LOL. Need to "undress" other one as well. They fit tight on a trailer, have to take them for IDOD tomorrow before I return uhaul
    #22
  3. katit

    katit Been here awhile

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    Need some help with wiring. Have bunch of questions with images. Look and tell me what do you see. What should and should not be there. I removed fairing harness and now it's looking pretty much clean/stock but I do have some suspicious pieces.

    #1 brown wire was not in main harness, found inside light housing connected to fairing. Removed, correct? It was hooked to battery directly
    #2 Rubber/metal speaker or something? Connected with electric tape/etc does not look stock. What is it? Was mounted to bracket together with relay in #5
    #3 Connector taped and tucked below brake master. Coming off main harness. What is it for?
    #4 Brown/white stock looking plug, was plugged to fairing wire. I assume it just goes back to brown/white terminal on board?
    #5 here, what is this junction, is it stock?

    Anything else jumps at you?

    IMG_5144.jpg
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    Attached Files:

    #23
  4. PaulBarton

    PaulBarton Long timer Supporter

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    Here's a wiring diagram for what should be your bike. BMW didn't use any electrical tape at the factory so that is all a kludge by the previous owner or his representative. The Vetter fairing required these kind of splices and each mechanic has their own personal level of acceptance with electrical. Some of those electrical tape bundles look like relays that were covered.

    Good luck. When I started experiencing electrical gremlins the first season with my /5 I jumped in and found lots of electrical tape. Ended up buying new harnesses and re-wiring it that winter. Got rid of the gremlins ;-) You look like your ahead of the curve with what you're looking at. Maybe clean up those splices and use heatshrink...





    BMW slash 6 wiring diagram.jpg

    Edit: I just realized that diagram is for a 74 MY which is different from 75-on. Here's a link to one that should cover 75-on /6. https://bmwmotorcycletech.info/schematic1975,1976.htm If you click on the R90S link it will download a visually easy to follow if slightly less detailed diagram.
    #24
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  5. Pokie

    Pokie Just plain Pokie.

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    It can be difficult to correct wiring that has been bodged by a previous owner. Basic wire usage is, Red - raw power, Brown - ground or negative, Green is raw power after the ignition, White - high beam, Yellow - low beam, Gray or Gray with a Black stripe is the park light or running lights, Blue with a Black stripe - right turn signal, Blue with a Red stripe - left turn signal, Black is usually a horn wire often coupled with a Green with Black stripe for the horn power, Brown with a Black stripe is the grounding switch for the starter motor Blue is the charge light.
    #25
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  6. katit

    katit Been here awhile

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    Actually, I think I am in good shape now. Only one yellow wire was pinched with snap-lock , need to fix insulation. Don't see any other damage.
    Look at pics. Is this "speaker" stock? It was mounted neatly. I did hook battery and it was making "bzz-bzz" sounds on turn signals. BTW, signals work, all indicator works.

    Other than that, only ONE wire is questionable. It is female BLACK connector on picture. It was hidden under electric tape. It comes inside main harness going into light housing.

    P.S. According to schema black wire (SW) comes from starter relay to terminal on circuit board? What is it for, anybody knows? And why it was disconnected?

    wire.JPG IMG_5179.jpg IMG_5147.jpg
    #26
  7. FBB

    FBB Been here awhile

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    BMW decided people needed help to remember to turn the turn signals off.

    I’m not sure if the slash 6 had the turn signal buzzer on them or not.

    My 78 100/7 has the turn signal buzzer. I disconnected it. Damned annoying.

    On my /7 the turn signal buzzer was located under the left battery cover.
    #27
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  8. katit

    katit Been here awhile

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    So it is original? Why all this tape then?
    #28
  9. FBB

    FBB Been here awhile

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    I’m not sure if it’s original to the /6 or not. Someone more knowledgeable may chime in and say.
    If it isn’t original, maybe someone thought BMW had a great idea on later models and added it to your bike.
    #29
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  10. katit

    katit Been here awhile

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    Doesn't look original. If it's not, I will leave it out then..
    #30
  11. Jim K in PA

    Jim K in PA Long timer Supporter

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    Not original.
    #31
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  12. katit

    katit Been here awhile

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    Parts should come in soon, I wanted to clean pan before oil change. My 5yo did most of the job by taking bolts out. Oil drained (nothing criminal, just thick darkish oil). Filter out (old style with 2 o-rings). But I can't get pan out. I banged on it pretty hard with rubber mullet, no luck. Any tricks? Gasket looks thick, about 1mm. Didn't want to put any metal wedge in it but it just doesn't come out with rubber mullet. Need advice.

    Also, look at plastic air plenums. They both were kinked. I guess it's a result of over-tightening clamp? Something to worry about?

    My car lift kind of works as a bike lift while I am waiting on proper lift as a present :)

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    #32
  13. melville

    melville Long timer

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    The random black wire in the headlight shell should be the one that can be used to set up an 'always on' headlight. It will actually cut power to the headlight when you run the starter.

    Some of the wiring schematics will show "US Version" and "UK Version", where US Version is setting up an always on headlight. Even though that wasn't the set up until 1978. Note how your /6 has a light switch in the left controls and your /7 doesn't. BMW put some extra wires in the /6 harness to cover several models and markets.

    There's another random wire in the headlight shell, which if you suss it out, is for the lever mounted brakelight switch for the drum brake on the R60/6. It's probably tucked away behind the turn signal relay.
    #33
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  14. melville

    melville Long timer

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    Oh, on removing the pan--put the drain plug back in. Lightly snug it. Then stick your 8mm Allen wrench in it, with the long side sticking out. While holding it up in the hole, whack the end with a soft rubber mallet. Be ready to catch the sump.

    DO NOT TRY TO WEDGE SOMETHING INTO THE GAP!!!!!
    #34
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  15. OldCrustyStuff

    OldCrustyStuff Adventurer

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    Another trick I use on oil pan is a block of wood to try to nudge it side to side with light dead blow hammer. A 12” chunk of 2”x4” ripped lengthwise gives you a block that extends out about perfectly to tap on. Fwiw
    #35
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  16. Pokie

    Pokie Just plain Pokie.

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    To get the oil pan off, I have a very sharp pallet knife that I drive into the gasket, has never let me down.
    #36
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  17. katit

    katit Been here awhile

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    Sorry guys for not responding earlier. After posting Q on oil pan I googled and found Snowbums article on this. Heat gun worked. What I found is that everything looks good and clean. No metal shavings or anything like that. Good chance to clean it and piece of mind.


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    #37
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  18. katit

    katit Been here awhile

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    Did some work with electrics. Checked and re-checked trying to tidy up wiring. One pinched wire I had to cut and re-solder (cut in order to put self-sealing heatshrink).

    End result - all blinkers work. Headlight (park, low, high) - all work. Headlight ON when ignition ON. Changed cover lenses on back from red to original amber. On fronts - don't tell me they are not straight :) Yes, I just bent them down for now. When I will be working on forks - I will replace those brackets.

    Brake light works either from front or rear brake. It's interesting to see how they come from "sleep". Blinkers didn't work for a second or two, I guess relays needed some time to wake up. Same with brake lights. But now all works good.

    BAD:
    1. Turn indicator on dash does not work. I assume it's PITA to fix that bulb?


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    #38
  19. katit

    katit Been here awhile

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    Didn't see any other wire unused. Actually I did find stock blinkers unplugged but I took care of it promptly. So, what do I do with this black wire? Should I just put it on "reserve" terminal? How does it come from a factory?

    I found those 2 wires under tank covered with electric tape (on picture). I assume it's horn. What kind of horn and where is it mounted? This M8 bolt and bracket on same picture? I had 2 horns mounted on fairing bracket and powered via faring wires.

    Also, what is this yellow switch on handle bar? (pic) Markings gone. I tried black one and I can switch low/high beams, so what this yellow for? I noticed backlight on speedo comes on/off when I flip it but?
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    #39
  20. PaulBarton

    PaulBarton Long timer Supporter

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    Those two wires look like the horn. Colors match to horn wires. My /5 had a very anemic stock horn...not sure how much improvement was made on /6 (not much I'm sure). I sourced a dual Fiamm set up with relays and BMW mounts from Tom Cutter at Rubber Chicken Racing Garage. He had the the "kits" already assembled so it was a single purchase. Not cheap but clean install. You can source the same horns (Hi/Lo Fiamm) from a variety of places and build your own relay wiring for less money. The RCRG kit came with BMW mounts that made mounting the horns to the frame clean and easy.

    In your case, you very likely can transfer those horns from the fairing and may only need to transfer the relay harness (I assume there was a relay in the "fairing wires") to under the tank. Add the frame brackets and you're good to go.

    FYI - I can startle awake distracted soccer moms with my dual Fiamms which the stock /5 horn would not do.
    #40