My 71 R75/5 Restoration

Discussion in 'Airheads' started by nevada72, Apr 23, 2019.

  1. Pokie

    Pokie Just plain Pokie.

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    Looks dreamy!
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  2. nevada72

    nevada72 Milwaukeeish

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    Well here's where I confess that I wasn't convinced that I was missing #3. To me it looked like the part was in there. I got the whole thing together and then something just didn't seem right. I had to adjust the clutch too much and it just didn't feel right. Then I was looking in my clutch box of parts and found 2 part #3s. :fpalm It was at that point I thought - "Dammit - Pokie was right. I should have just assumed as much." So I took it apart, installed all the parts, and it adjusts and works the way it should. So thanks Pokie!

    Other than that some fairly simple tasks. I took the tank off and attached the spark plug wires. I had to makeshift one of them as the contact at the end of the wore pulled off when I pulled the wore out of the coil. Again, the doner bike came to the rescue and it provided that little metal piece. So that's all together.

    Another bonus from the donor bike - the horn. It actually works! I didn't have one and man, people are proud of those. I tested it on a battery and yup - Honk! It's kind of grungy looking so I'll clean it up and paint it.

    Other than that my bezel and gasket showed up for the speedo. The donor bike speedo will look pretty good once together and the tach will work.
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  3. nevada72

    nevada72 Milwaukeeish

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    More progress. I got the Rocky Point ignition the other day and installed that. I love it! It is soooooo much nicer to work with than the contraption BMW uses. Yes, installed properly that contraption works pretty well, I'll admit. But I like this better and I don't care about originality to that extent.

    ignition installed.jpg

    I got the speedometer bezel from Motobins. It solves my speedo issue nicely. This is the one from the blue bike. The original ring was toast.

    speedo.jpg

    On Saturday I'm having an Airheads tech day. The plan is to do a first start. If all goes well, and I can't imagine why it wouldn't, we'll get the bike running and balance the carbs. After that it will be a matter of getting the lights and blinkers installed, as well as the front fender. Then that's it - Pau Hana! (in honor of Big Bamboo)

    If anyone happens to be in the SW Wisconsin area on Saturday, you are invited to join.
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  4. nevada72

    nevada72 Milwaukeeish

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    For whatever reason, Spring doldrums, age, mental decline, whatever it may be, I'm just not seeing a clear path on wiring the bike up. It's a bit frustrating as I have rewired quite a few bikes. And hell - by trade I'm an electrician! Which, of course, isn't the same as being an electronics expert. But I at least understand current flow. So with that in mind some questions -

    Here's what I have in the bucket for the bike to run (I would imagine) -

    wiring.jpg

    It's -

    2 x solid green - coils and other switched power?

    1 - red - raw power

    1 - black - horn

    1 - grey - lighting

    1 - brown - ground

    Do I have that right?

    Here's the switch diagram -

    ignition wiring diagram.jpg

    Based on the above diagram, and considering the wiring I have outlined above that, would the connections be -

    2 x solid green - blue terminals

    1 - red - raw power - red terminal

    1 - black - horn - NA

    1 - grey - lighting - Blue terminals

    1 - brown - ground - ground bus in headlight shell

    Does that make sense?

    As far as the starter - I'm a little lost on which is the lead to the starter relay. My understanding is that the handlebar switch is a simple momentary switch that would have a hot (blue terminal?) lead connected to one side of the momentary switch, and then another wire connected to the other side of the momentary switch - what wire runs to the relay?

    Again, I feel a little stupid even asking these questions. This is typically the area that I help others with. But again, for whatever reason I'm not feeling confident.
  5. Pokie

    Pokie Just plain Pokie.

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    At the handlebar switch, the starter is a grounding switch, the wire color at the switch is brown with a black stripe. The ground strip at the switch is a simple brass strip that is grounded by one of the switch holding screws, that's why the starter button won't work if you have the switch hanging by it's wire, it NEEDS that grounding point (the screw). It's not uncommon for the brass grounding strip to be damaged by the switch not being fitted properly.
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  6. Franque

    Franque Nilé na sohakélwa manga

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    One suggestion: if you can use proper DIN colored wiring (I'm not sure if this kit is or isn't, I thought it might not be), and if you learn the DIN wiring system, it makes reading/understanding the harness make complete sense.
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  7. Pokie

    Pokie Just plain Pokie.

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    The correct colors are available, you just can't get them at the local hardware store. I use Rhode Island Service http://www.riwire.com/ they have fast turn around BUT it does take planning.
  8. nevada72

    nevada72 Milwaukeeish

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    All of the wiring is oem save for the switch itself which I basically understand. It's Off/all on except headlight/all on with headlight. I did take another look at a wiring diagram, as well as the bike itself, and found the brown/blk wire in the bucket. It appears they grouped the wiring in 3 bundles - run circuit/rear tail light circuit/starter relay wire and one more wire I haven't addressed - neutral?

    I was hoping the switch was a hot switch not a ground switch as I powder coated the bars and bought reproduction switches from EME. I don't recall seeing a brass tab on the new switches. I'll have a look once the garage comes up to over 40 degrees. These cold mornings are slowing me down.
  9. Franque

    Franque Nilé na sohakélwa manga

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  10. nevada72

    nevada72 Milwaukeeish

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    Made good progress tonight. Bike turns over and has spark, so apparently I did something right.

    The wiring worked out just fine. At least to get it to the point it's at, which is good enough to start the bike. The next challenge will be the instrument lighting. I'm sure it will all make sense once I have a look.


    Brook knows his stuff. I've referred to his website often.
  11. nevada72

    nevada72 Milwaukeeish

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    Alright alright, alright! (he said in his best McConaughy voice) - the bike runs! Not only does it run, it appears to run well!

    Backing up a bit, the Airheads Tech Day started early at 7:30. Randy, our local Air Marshall showed up with specialized tools and most importantly, his knowledge. Scrapper, from this forum showed up shortly thereafter. Which was great because these two guy probably did more wrenching on my bike than I did! :D My only excuse is I was busy fetching coffee and Kirkland granola bars for the group. Shortly thereafter 4 more showed up for a total of 6. Not the biggest crowd but things being as they are I wasn't surprised. Between COVID and the nice weather, I get it if folks wanted to just ride.

    Anyway, we got to torqueing critical fasteners, adding fluids, and Randy statically set the timing to make for an easy first start. I had never seen it done this way - he set up the spark plug the way one would check spark, laying on the cylinder and grounded. He then rotated the motor, ignition on, and waited to see (and hear) a spark. He then checked the timing port and looked to see if he was close, which he was. Then it was a simple matter of adding fuel, installing spark plugs, and hitting the start button.

    At first the motor just turned. I was a little disappointed but after Randy fiddled with a few things we tried again - boom! Actually a bunch of booms. The bike started right up and idled pretty well. Randy spent some time making minor adjustments to the idle, synching the carbs, and a minor tweak to the timing.

    After that it was time for lunch. It was a nice sunny day so we sat in my driveway and had Italian Beef as prepared by Ms72 and what we pretty much serve at all tech days. After lunch we felt we had done the main list and elected to break early so people could enjoy the day. One of the attendees, Mike, rode his sweet 83 RS down from NW Wisconsin - about 3.5 - 4 hours depending on route. So he needed to get on the road as well.

    The next main thing I wanted to do was get the front brakes working. I had sent them to the vapor blaster and he took them totally apart so there was a little reading to do to put it back together. I went to Brook's site (1973 BMW R75/5 Rebuild: Project Index | Brook's Airhead Garage (reams.me) ) and did a little more reading. Unfortunately without complete comprehension as I reversed the springs. Which explains why the brakes wouldn't adjust. Fortunately I had a spare brake assembly (or two) to use as a reference. In fact I used it as more than a reference, I just tossed it on the bike. And why not? It looked good, the shoes have life in them, and it's put together right. I cleaned and lubed it. It adjusted just like that.

    Today I cleaned off the lift of parts and tools, re-checked fasteners, and decided to fire it up again. Yup - started immediately. Enrichening circuit works just as it should. After it warmed up a bit, with the EC off it settled into a nice idle. Then I figured, seeing as it's on the ground and running, I might as well take it for a short ride. So that's exactly what I did, no headlight, gauges, no nuthin. And it was great. Clutch is perfect. Gears are perfect. Steering and suspension - perfect. It was a pleasure to ride and felt even better than prior to starting the restoration. And it ran pretty damn good back then. But it was ugly and leaked like a sieve.

    The ride was brief. As I understand it, without the charging light connected the bike won't actually charge. That and riding a motorcycle without a headlight and tail light isn't the safest thing to do, even in our quiet sub-division.

    When I got back I got the front turn signals together, but that was about it. It was Miller time and I felt I deserved a cocktail to congratulate myself.

    Day 1 running.jpg
  12. Pokie

    Pokie Just plain Pokie.

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    Don't look now but I think your parts bike fell over!
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  13. nevada72

    nevada72 Milwaukeeish

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    Hah! Yeah, it gently fell over on purpose so I could soak the stuck right cylinder. It almost made it to the stand yesterday. But I figured I should finish the red bike 100% before putting the blue one on the stand. So there it will sit until I decide what to do with. Restoration? Parts? Crappy looking runner? Sell whole? I'm just not sure. I have almost all the parts I need to make it a running, riding bike.
  14. Franque

    Franque Nilé na sohakélwa manga

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    Depending on your amount of free time, it'll probably be more profitable in the long run to get it running.
  15. Disston

    Disston ShadeTreeExpert Supporter

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    A running bike is always preferable from both a buyers and sellers perspective.
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  16. nevada72

    nevada72 Milwaukeeish

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    Valid points. What I really need to decide is whether or not I want to invest the time. The red bike was a 2 year project. Yeah, that was a complete tear down and refurbish so there was a lot of lead time that added up. One of the Airheads offered me $1000 for the blue bike and I told him he could have it with all the take offs from the red bike. The only thing he would need is a set pf jugs and pistons. Or at least the right side. We made a loose agreement that if I had to get rid of it, call him. If he has to have it, he'll call me. Either way I'm not in a hurry to sell it because I may just decide to make it run.
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  17. nevada72

    nevada72 Milwaukeeish

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    So the next thing to do is wire up the instrument lighting. To me the design is a bit strange in that it's a total loss charging system and something as simple as a burnt out bulb means you aren't charging, if I understand it correctly.

    Based on this (zoomed screenshot of a ) wiring diagram -
    lights wiring.jpg

    .....it seems pretty straightforward. Battery charging light, neutral indicator, and oil pressure light all connect to the green, which is my big white terminal strip, and the other side of the lamp connects to blue, blue/orange, and green/orange wires respectively. Does that sound rights?

    High/Lo beam seems pretty straightforward.

    Blinkers - it's been a while but I would imagine the blinker flasher gets connected to the green circuit, then on to blinker indicator light on the shell (connected in series), then on to the common for the blinker switch. From the blinker switch the blue/red and blue/black got to the blinkers themselves. Is that correct?
  18. Pokie

    Pokie Just plain Pokie.

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    Having them all connect to the green wires makes sense as the green is switched power and each of those switches are grounding switches.

    Yes, the green wire should go to the switch that switches the power to left and right turn signals (red stripe for left and black stripe for right, think port and starboard), the flasher will interrupt the green wire before it goes to the switch.

    On a 1971, the turn signals will ground through the steering head, on 1974 and later there is a ground run to the turn signals as well.
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  19. nevada72

    nevada72 Milwaukeeish

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    All makes perfect sense - thanks!

    Funny you mention the nautical reference because I was going to opine that I would have done the red strip on the right, or red for right and red right returning.

    On the blinkers themselves - I ran a ground wire to the fronts to make sure I had a reliable ground. My career in medical equipment has taught me that using bearing assemblies for grounding is not 100% reliable.
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  20. nevada72

    nevada72 Milwaukeeish

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    Made more wiring progress. I have all of the instruments lights working. Part of the problem is the wiring color from bike to bike seems to vary. Both of my 71s have the stock wiring harness. But the wire colors don't match exactly. For example, the blue bike has a blue wire with purple tracer going to the neutral light. The red one has blue/brown. Sounds like an easy deduction to assume they are meant to be one in the same. But the brown was super faded whereas the purple was vivid. The diagram above looks like blue orange. In the end, through a process of elimination, as well as having taken a LOT of photos during disassembly (thank God!), I was able to get it figured out.

    Now the only issues I have are on the hi/lo/horn switch. I have hi/lo figured out easily enough. And I believe I have the horn switch figured out - needs to make ground contact. But because the bars are powder coated that's becoming a challenge. I'll figure that out. I'll probably just need to remove some powder coating at the clamps. But there's a green with red tracer at that switch and I have no idea what that is for. I'll look at the wiring diagram and figure it out but it feels like everything is accounted for with the hi lo circuits (wht/yellow, white, and yellow wire) and the horn circuit (blk). I can't imagine what that green/red is for. And it doesn't seem to ring out to anything else. Oh well.

    Other than that, the blue bike is finding a new home today. I decided to let it go to another Airhead member. It will be a great project for him as he is retired and has done a number of full restorations with good results.