Reincarnating an 81 R100RS

Discussion in 'Airheads' started by theDQG, Oct 1, 2017.

  1. theDQG

    theDQG Been here awhile

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    In the limited time that I've had it, it has performed flawlessly and controlling my bike from my iphone as well as performing diagnostics is just next level tech stuff. My favorite thing to do is sit some distance from the bike and ping it every time someone comes within inches of touching it. They often recoil and stare at the bike as if it's from another planet. Gives me the giggles every time.
  2. theDQG

    theDQG Been here awhile

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    This is my first BMW bike so I will be asking a lot of dumb questions, as I familiarize myself with how the bike works, inside out.

    I am studying this wiring diagram to figure out how the electronics of this bike works, hopefully it's ok to post this diagram here:

    R100RS-RT Wiring Diagram - public.jpg
  3. theDQG

    theDQG Been here awhile

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    alt.JPG

    The alternator below, and above, the upgraded diode board, a.k.a., rectifier, correct?

    regulator.JPG
    The below four wires come from the diode board, a.k.a., the rectifier and plugs into the voltage regulator, correct? How does the BMW regulator work? Brown and black from alternator? What do the two blue wires do?

    Also the black and blue two wire connector above is for what? Black receives from the Starter relay and goes to starter, correct? Blue goes to regulator, correct? Where does it come from?
  4. theDQG

    theDQG Been here awhile

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    startercable.JPG

    I hold in my hand the starter cable, where it hooks to the positive terminal of the battery, correct? From what I can tell, it's 4 AWG. Right? The left, snipped, red wire goes to the diode board, a.k.a. rectifier? They both join at the starter, because it's both a starter and solenoid?
  5. Plaka

    Plaka Brevis illi vita est

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    the two red wires join because it is just a connection point.
  6. Plaka

    Plaka Brevis illi vita est

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    it is dubious if the diode board is an "upgrade". depends on who it came from. it Is aftermarket. some of them are crap. some of the oversize charging systems use their own diode boards.
  7. Plaka

    Plaka Brevis illi vita est

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    the starter assembly contains a solenoid that acts as both a mechanical solenoid and as a high amperage relay. the starter proper is just a motor with a gear on one end. the solenoid moves that gear into engagement with the flywheel AND closes big contacts that route big battey amperage to the startr motor. common to have more connection points there. bmw was saving on copper.
  8. theDQG

    theDQG Been here awhile

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    The snipped red goes to the diode board?
  9. theDQG

    theDQG Been here awhile

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    Repeating my questions here since they were not answered. I would like to receive clarification.

    From what it seems- the black and blue wire that come out of the chain cover: the black is from the spade on the starter, and the blue is D+ from the voltage regulator?

    Still trying to figure things out, would appreciate any insights. Thanks all.
  10. theDQG

    theDQG Been here awhile

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    Took a closer look at the carbs. Each carb has one screw missing, and one has one rivet missing from the backside. I assume the screws are easy to source. But the missing rivet concerns me. Should it be fixed?

    backside.JPG outside.JPG
  11. pommie john

    pommie john Long timer

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    The alternator uses field coils in the rotor not a permanent magnet rotor. The voltage regulator controls voltage by changing the current going to the field coils which is the brown black wires. Effectively it is changing the strength of the magnetic field to control the alternators output.
  12. Steve in OC

    Steve in OC Been here awhile

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    Which aftermarket diode boards are crap?
  13. Plaka

    Plaka Brevis illi vita est

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    perhaps search here for the ones people are complaining about. one problem is a particular assembly screw that has a heat problem. Rick found this problem, and corrected it early. But he noted the people knocking off his stuff were copying the errors too----but not correcting them. I think one is gone, the one with the red breadboard. don't quote me.
  14. Plaka

    Plaka Brevis illi vita est

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    yes and yes. you can source both parts from bing. the riviet is holding on the cover over the butterfly shaft. you do not want a leak ther. but look at the exploded diagram of the carb. if the shast has o-rings on both ends then no biggie.

    the missing screw on the choke cover will allow air to leak in ther, or gas to leak out. same as when the gasket for that cover goes bad. new gasket andscrew.

    do but the bing carb book from bing. it is cheap and will save you many questions. And get the charging book from rick jones. Same deal.
    theDQG likes this.
  15. theDQG

    theDQG Been here awhile

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  16. theDQG

    theDQG Been here awhile

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    How beneficial would the charging book be for me when I am planning to wire the bike from scratch? I am not going to eliminate the charging light because I've read that it's essential to the airheads.
  17. dave0

    dave0 Been here awhile

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    Yes on the Bing manual. Yes on the charging book. Sounds like you're doing a re-wire using the same style charging system.
    theDQG and Kiwiabbo like this.
  18. theDQG

    theDQG Been here awhile

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    I have put together a shopping list and have sent it to the Bing people to get it processed and hopefully will get the goods soon.

    Today, I was thrown a curveball and got some bad news. The lease renewal on the shed I have been renting to build my motorcycles, has been declined. I have until July 31 to vacate the shed.

    So that gives me six weeks to finish the build. And I would rather do that- finish it and get it on the road before I have to vacate the shed, instead of packing stuff up and finding another place to continue the build.

    Hopefully with the help of this forum I can try to continue to work on the bike and put in all the free time I have, on it.
  19. theDQG

    theDQG Been here awhile

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    Are there good AM carburetor boots substitutes? The rubbers that I have are hard and brittle- I could boil them in water with a dose of wintergreen, but- if there are good AM options, I'd rather go for that.
  20. theDQG

    theDQG Been here awhile

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    Don't everyone commiserate with me at once.