Back on an Airhead - 1975 BMW R90/6

Discussion in 'Airheads' started by tete, Aug 27, 2012.

  1. Kai Ju

    Kai Ju Long timer

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    Take said screwdriver, insert between the chrome ring and the housing at the six p'clock position and twist the screwdriver.
    That should pop the chrome ring off.
    Once it's off you'll see how it works.
  2. tete

    tete clown shoes

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    Thanks
    It worked and unfortunately here is what was there.
    [​IMG]
    [​IMG]
    [​IMG]

    It looks like the some thingy that goes on the right ( if looking directly into the bucket) for what ever reason was covered in plastic and tape. I dunno this looks like it will get interesting.

    One thing to consider if commenting is that I have an acewell ready to install. But most important it is getting the instruments (headlight and tailights ) working good. Especially that super dim light. Which I suspect I'm using the parking light and my actual headlight is rubbish
  3. tete

    tete clown shoes

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    Ok so here are the problems to better elaborate.

    1. Headlight is dim. The white switch is in the down position when it's on which I think suggest ima actually using the parking lights. When I put the switch in the middle or up position there is no lights

    [​IMG]

    2. The blinkers work fine, however when blinking the tail/brake light flashes

    That's the extent of my issues.
  4. tete

    tete clown shoes

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    I was trying to figure out where in the Clymers it shows what this cube shaped thingy is on the inside right of the headlight. is there a wiring harness I can buy that perhaps eliminated alot of this?
  5. Solo Lobo

    Solo Lobo airhead or nothing

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    Bet the alu one on the right is the flasher relay
  6. chasbmw

    chasbmw Long timer

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    On the right is the headlight relay, the flasher relay is on the left. (as you look into the headlight).

    Looking at the photos it looks as if the headlight relay does not have any contacts? What the bike needs is a new relay wired as per wiring diagram?

    Charles
  7. Kai Ju

    Kai Ju Long timer

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  8. craydds

    craydds Long timer

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    Not to steal Tete's thread, but we are both installing an Acewell, so... Charles, as I look at the wiring schematics, I cannot see why the brown wire needs to be grounded to the frame. I don't doubt your actual experience, but I don't see the necessity of "re-grounding" the brown wire, as it appears that it already goes to ground (again, based on my interpretation the schematics).
  9. tete

    tete clown shoes

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    Does anyone have a daigram of the left switch / lights assembly. I believe I hve a bad switch.
  10. tete

    tete clown shoes

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    I'm trying to figure out how this might go together. [​IMG]
    Is there a ball that goes at the end o that spring?
  11. tete

    tete clown shoes

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    Ok I got the switch back together properly. But I follow the route and I believe the relay must be wired incorrectly. However I can't seem to find a diagram showing which female end goes to which male end. I wired it up the way it was and it did not work. The PO was obviously in there messing things up because there was electrical tape and messy connections everywhere.

    So essentially I need a headlight switch relay diagram. Electrical is very frustrating. Especially when the information is not out there in the same way mechanical issues are.
  12. chasbmw

    chasbmw Long timer

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    There could be problems if the PO has replaced the LH switch unit. I understand that the later switch units have different wiring, if you can find a wiring diagram for a /7 round about 1977, then this might help. Does your LH switch unit have an on/off function? In the US legislation in the 70s ensured that bikes had to have lights on all the time, but I'm not quite sure when this was enacted. According to my wiring diagram a 74 R90/6 does not have a headlamp relay, though my bike has one fitted. I will go and check the bike and see, either today or tomorrow.

    Euro bikes will have an on/off switch, so be careful as to which wiring diagram you are looking at. The function of the headlamp relay is to prevent the full headlamp current running through the headlamp switch.

    The earth for the instrument lights runs via the brake fluid low level switch to an earth by the coils, if that is still present then you are OK.

    Charles
  13. tete

    tete clown shoes

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    Yeah my instruments light up fine as do my turn signals and brake lamp. Parking light and brights (if i push tht button down that is.) work fine it seems.

    Just the "stay on" headlight won't happen or stay on bright wont happen.
  14. tete

    tete clown shoes

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    Question: With total disregard to handling as I am aware of the characteristics. Do we know if the firestone Deluxe tires will fit the typical size R90/6? I believe 18 x 4.00 and 19 x 3.25 ?
    Im concerned with the rear swing arm rubbing and the front fender rubbing - the tires seem to be balloon like.

    thanks in advance.
  15. tete

    tete clown shoes

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    Ok, so I have not installed my acewell because of issues I am having with my headlight not working.

    I'm still dealing with that.

    I got a new headlight switch and a new relay.

    Here is the issue. My switch is slightly different.

    Pictured in my old on the left and new one on the right. Fits perfect but the switch is different.
    [​IMG]
    Also the wiring is different. Once again the old on the left new one on the right
    [​IMG]
    Anyone deal familiar w this?
    Which wires may go where? The new harness does not have a red, grey or solid brown wire?
  16. tete

    tete clown shoes

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    It looks like, according to clymer, my new switch is off a R100. Now I have to figure out a way to mate it to the R90 set up.
  17. disston

    disston ShadeTreeExpert

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    It looks to me like your old switch is what I hear people calling a European switch, it has an on/off for the headlights. The switch on the right does not have an on/off so the headlights will be wired to stay on all the time.

    You can probably figure this out if you look at two separate wiring diagrams that each feature one of these, maybe.

    That's what it looks like.
  18. tete

    tete clown shoes

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    Yep, You are right now I must figure out how I can wire the new switch in. I actually prefer always on.

    Here is what I do know.

    White = Brights
    Yellow = Low Beam or regular beam
    Brown is ground

    Brown w White = horn
    Green w black stripe= horn

    So i need to figure out what the Yellow with White stripe is

    Then I need to figure out f I can use my old relay or do I need a different one. Also need to figure out which goes where.

    not fun. The best part is when I'm all done figuring this out I'll take it apart for the Acewell. One thing at a time.
  19. tete

    tete clown shoes

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    What can I connect the brown/white stripe wire / as well as the green wire to the switch? looking at this just makes me more confused. Can't i just go back to cleaning carbs and painting stuff.

    For the record I have a R90/6 and am trying to retofit the R100 switch to work (this has always on headlight)

    OK so here is how I look at it. According to clymer.

    I should be able to connect the brown w white striped wire for the horn switch to the clutch switch one on the R90/6

    The green/black striped wire I should be able to connect to the contact board.

    That should take care of the Horn there is no horn relay on the R90/6 but there is on the R100 that the switch was designed for .

    On the headlight side is where it gets tricky/confusing for me. because I have to use the relay. What if I simply match up the left over wires (4 of them) to the relay from the /6? here is the diagram

    On the left is the R90/6 and on the right is the R100/7
    [​IMG]


    There is no Red on the new harness but Perhaps I won't need that with the "always on" switch.. i dunno. ungh.
  20. tete

    tete clown shoes

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    Ok so I figured it out. Got to bridge the green over from the ignition. The plan for the horn didn't wrk out so ill just hook it up the same way it was originally. Gotta find those wires.

    Ill draw up a diagram once I'm done for any future inmates that may find it useful.