R80RT Rebuild

Discussion in 'Airheads' started by op48no1, Aug 18, 2016.

  1. op48no1

    op48no1 Never Forget Bowling Green

    Joined:
    Jan 2, 2014
    Oddometer:
    672
    [​IMG]

    [​IMG]

    Fill my eyes with that double vision
    No disguise for that double vision
    Ooh, when it gets through to me, it's always new to me
    My double vision always seems to get the best of me, the best of me, yeah-ah

    * * * * *

    I've been working almost non-stop since Friday and getting four to six hours of sleep a night. My brain is fried. More information will follow.
    Cogswell, JimGregory and infinityedge like this.
  2. SculptD

    SculptD Smells like tech

    Joined:
    Jun 20, 2013
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    917
    Location:
    SF, CA
    Nice! But I believe mirrors are required in the Commonwealth, no?
  3. op48no1

    op48no1 Never Forget Bowling Green

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    Yeah, like that's gonna stop me from riding it.

    No gauges, either.
    Jim K in PA likes this.
  4. op48no1

    op48no1 Never Forget Bowling Green

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    I need to take pictures of the wiring. I had some space/routing issues and ended up with an overly-complicated three harness solution. Not entirely happy with that, but it's fairly tidy and everything works.

    The Sumitomo connectors are probably a lot more robust than the Molex, but they are bloody huge.

    I still need to sort out the instrument wiring, plus make or buy an oil/neutral harness. And the fairing, of course. Still a lot of work left to do.

    I had a lot of trouble getting the engine running well enough to ride yesterday. First, gas was pissing out of the left carb, then the right carb, all over my garage floor. Suspecting crap in the tank, I swapped in the R100 tank and carbs. Then it turned out the real issue was I had loosened the bean can too much and the thing rotated to full retard. Like the owner.

    After that I went out for a twenty-mile or so ride. Engine runs fine. Carbs probably need a little fine tuning. The Siebenrock kit doesn't make as much power as the Moorespeed setup. Really, the only difference is the pistons and the smaller-diameter combustion chambers.

    I swished the R80 tank with gasoline, emptied it, and removed the petcocks. No obvious dirt in the screens, so that's; good. Earlier I had washed the tank out thoroughly with soap and water, but we don't want blasting media residue in the engine.

    I don't like narrow bars. The front end is a bit wobbly. Typical mono head shake, but I need to check the steering bearings.

    I made a left turn on a street corner and nearly low-sided. Nice big rear end slide. I guess new tires and gasoline don't make for a healthy combination. Crash would have been a fitting end to the first ride. I was pleased with myself for riding it out without going down.

    I was looking at the R100 wiring the other day for a reference and discovered that the big fat power cable going from the battery terminal to the m-unit was rubbing on a frame bracket and was almost cut through. Holy crap, if that had made contact the bike would have caught fire. So I guess at least one good thing came out of the R80 project.

    I'm pretty impressed with this battery I got at Auto Zone. I cranked and cranked and cranked the hell out of it and it never showed signs of weakening. Hopefully it will last. BMW wants $190 for their Exide AGM battery. What a joke.

    I wanted to buy a PC680 but didn't want to wait to mail-order. Batteries Plus has them locally for $159 dollars, which is substantially more expensive than even the Odyssey online price.

    Anyway. Now I have one and seven-eights airheads. Need to take a break.
    JimGregory likes this.
  5. op48no1

    op48no1 Never Forget Bowling Green

    Joined:
    Jan 2, 2014
    Oddometer:
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    Because I enjoy embarrassing myself...

    Just got an email from my sister with a link to a Facebook photo posted by one of my sister's childhood friends. It's a publicity shot from the WHMT public TV auction about nineteen million years ago. That's me, evidently, and my sister in pigtails. Seventies hairstyle. I guess someone donated an Easter bunny to the auction. Cripes. What a nerd.

    [​IMG]
    JimGregory likes this.
  6. ME 109

    ME 109 Long timer

    Joined:
    Jun 25, 2009
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    5,562
    Location:
    Albury Australia
    Henry, I'm wondering why an electronics wiz wouldn't have a fuse on such a wire?
  7. op48no1

    op48no1 Never Forget Bowling Green

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    Oddometer:
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    There is a fuse. It's called the m-unit. For every fuse, there needs to be a wire from power to the fuse. What do you do? Put a fuse in the wire going from the battery to the fuse? And then recurse infinitely, until your wire is nothing but fuses?
  8. op48no1

    op48no1 Never Forget Bowling Green

    Joined:
    Jan 2, 2014
    Oddometer:
    672
    Take the instrument cluster bulb bridge and drill out and remove the connector pins:

    [​IMG]

    Chop off the unneeded illumination bulb arms:

    [​IMG]

    Trim the unused traces from the circuit board:

    [​IMG]

    Clean up the corroded PCB contacts and reinstall the bulbs. (What a crappy design, unplated bare copper. Sad!):

    [​IMG]

    Solder wire to the circuit board pads. Careful, this flexible PC material doesn't like heat:

    [​IMG]

    To be continued.
  9. op48no1

    op48no1 Never Forget Bowling Green

    Joined:
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    Oddometer:
    672
    I put some J-B Weld on the back side to hold the wires.

    [​IMG]

    I need 12 wires to connect the instrument pod. With the pins removed there are 12 holes in the light bridge. Some of the wires just pass through and do not connect to the PC board, e.g., speedo, tach, unswitched power, and the mode switch. Switched power and ground pass through but also connect to the board.

    Epoxy takes time to cure. No more progress pending until tomorrow.

    * * * * *

    Something occurred to me this evening while I was looking at the gauge lamp PCB. Motogadget would have you use diodes to combine the Turn-L and Turn-R signals to operate a single indicator on the dash. Looking at the PCB, I noticed that both sides of the turn lamp connected to open pins rather than one side going to ground. So I thought to myself, "Self, what would happen if I connected one side of the turn lamp to Turn-L and the other to Turn-R?" I drew a quickie schematic to verify the idea, popped the lenses off the signals on the R100 and tried it out with clip leads. It worked.

    So why does this work? Say you turn on the left turn signal. Current flows from the Turn-L wire into the dash lamp and out the other side, then into the Turn-R wire, through the right-hand turn signal bulbs, front and rear, and then to ground. Same thing, only opposite orientation when you turn on the right turn signal.

    The turn signal bulbs are much higher power and therefore lower resistance than the dash lamp, especially with cold filaments. The little indicator bulb doesn't draw enough current to make the turn signals glow. Since not much current is flowing, the voltage drop across the parallel turn signal bulbs is low and the dash indicator sees almost the full battery voltage, hence it glows brightly.

    Electronics trivia question. If you connect a 100W light bulb and a 10W light bulb in series and plug them in, which bulb glows brighter?

    This saves me two diodes and the trouble of finding a way to mount and connect them. Now who's the electronics genius?
  10. op48no1

    op48no1 Never Forget Bowling Green

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    Tonight I bought some itty-bitty crimp female connectors to go on the tach and speedo signal pins. It shouldn't take too long to wire this all up tomorrow and then, in principle, I should have a working tachometer and dash lamps. Well, OK, I still need to wire the oil and neutral switches, but I can test the lamps without that. Speedo will need to wait, as I said, until I get the sender and make an interface board.
  11. KLEINE

    KLEINE oo

    Joined:
    Oct 9, 2012
    Oddometer:
    91
    Location:
    sometimes Amsterdam
    Nice work! The diode's suggested by Motogadget for the turn signal indicator are for led light indicator's I think. Is the way you wired it not the same as bmw does it? :lol3
  12. op48no1

    op48no1 Never Forget Bowling Green

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    Yes, it seems this is how BMW does it. I didn't check the bike schematic but it makes sense. You're right, this scheme depends on the gauge turn light working in both directions, which wouldn't work for an LED. Also, I think it would be problematic with LED turn signals.
  13. op48no1

    op48no1 Never Forget Bowling Green

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    I removed the speedo drive gear and trip reset knob from the inner plastic bracket, then filled the holes in both brackets with potting resin.

    [​IMG]
  14. op48no1

    op48no1 Never Forget Bowling Green

    Joined:
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    Oddometer:
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    I connected the wires to the header pins on the tach and speedo circuit boards.

    [​IMG]

    So this is good...

    [​IMG]

    Plus, when I tapped the tach and speedo lines repeatedly to +12V, the needles moved. Guess everything is working.

    Looks good on the bike.

    [​IMG]

    We have a couple of minor problems. While configuring the tach and speedo I discovered that the mode switch for the speedo is referenced to +12V whereas my black switch on the control pod is referenced to ground. I really don't feel like picking with the switch harness, connector, and wiring in the bike to change the switch. So I will have to build a little transistor inverter and stick it inside the gauge housing. A nuisance, but not the end of the world.

    Also, where the heck am I going to put the ignition switch?
    aptbldr likes this.
  15. op48no1

    op48no1 Never Forget Bowling Green

    Joined:
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    Oddometer:
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    Here's my switch inverter:

    [​IMG]

    I tested it with the speedo and it works. I can change modes switching to ground instead of to +12V.
  16. op48no1

    op48no1 Never Forget Bowling Green

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    I cut out the rectangular section that covered the pin area of the circuit board. It would have been cool to bring the wires up through the pin holes, but that would have made it impossible to service the inside of the instrument case, e.g., to change bulbs. I installed this pin header to connect to the gauge configuration inputs and the mode input on the tach. The handlebar pushbutton switch goes to the mode input on the speedo. I'm just going to leave the tach display set on voltmeter mode. The speedo side will give me odometer, trip meter, voltmeter (redundant) and clock.

    [​IMG]

    Unfortunately there was a slight interference between the connector and one of the bulb holders so I decided to cut the connector off. Once the speedometer is calibrated I really shouldn't need to mess with the configuration so not having the connector is really no big deal.

    I made a little cardboard box and am potting the switch inverter.

    [​IMG]

    I like transistors.
  17. Jim K in PA

    Jim K in PA Long timer

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    Mar 15, 2011
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    2,625
    Location:
    Pocono Mountains, PA
    You're a polarity-flippin' gangsta, Henry. :thumb

    Absolutely love this gauge cluster. Thanks for sharing the process.
    Uke likes this.
  18. R100RTurbo

    R100RTurbo Where was it we're heading to in this hand basket?

    Joined:
    May 23, 2014
    Oddometer:
    784
    Location:
    BC
    Not only that Henry, but you seem to be quite the Chick Magnet too, with your bunny club an all:killen
    Enjoying the wiring
  19. op48no1

    op48no1 Never Forget Bowling Green

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    Oddometer:
    672
    Yeah, chick magnet.

    One logic inverter. Tool for the modern political era:

    [​IMG]

    I torqued the heads, adjusted the valves (intakes were tight), adjusted the timing, and synched the carbs. Time to ride.

    [​IMG]
    Uke likes this.
  20. op48no1

    op48no1 Never Forget Bowling Green

    Joined:
    Jan 2, 2014
    Oddometer:
    672
    [​IMG]

    [​IMG]

    Well, I went out for another short ride. I think the black looks beautiful. Whether or not it's worth the pain of scratches and fingerprints remains to be seen. But it's lovely, and even more impressive in person.

    The engine runs perfectly. I am still at the phase where I feel a sense of dread every time I start it. This will wear off in time. I imagine if the engine were going to blow up it would have done it by now.

    The valve gear is quieter than on the R100. I need to check the R100's rocker bearings and axial play. I know at least one rocker needs to be shimmed.

    There's plenty of power. I came home and synched the carbs on the R100 (I hadn't readjusted them since swapping back from the R80) and went out for a ride. The thing that strikes me is that the R100 just feels more sorted out than the R80. A big factor is the R80's brake lever, which engages scary-close to the grip. I need to do something about that. Another thing is I am very uncomfortable riding without mirrors. Mainly the difference is the handling. The R100 feels solid and stable and riding it reminds me how awesome the Continental radials are. I put Metzeler Sportec Klassiks on the R80 and though I'm sure they're fine tires, they don't compare to the Continentals. I am reluctant to corner hard on the R80 yet after the other day's power slide.

    One of the improvements I got from the Continentals was a complete elimination of the typical Monolever head shake. I suspect the head bearings on the R80 are loose but experience says even once I tighten them there will still be some wobble. I guess that's why they call them B-M-Wobble-Yous.

    It took some time for the new seals on the R100 to break in, and I have an all-new front suspension on the R80. I imagine the front end will start to feel more supple in a few thousand miles.

    As with the R100, the rear brake doesn't seem to do squat. I was hoping the new-style shoes and actuator would improve things, but no. I guess it's just par for the course. No big deal. Brakes just slow you down.

    I much prefer the wider bars on the R100. An inch and a half on each doesn't seem like a lot, but it is. Maybe one day I'll do something about that.

    Anyway, it's all very cool. Seems like we have a winner here. There's still some work to do, but it's good. Too bad I have to go back to work tomorrow. Ugh.
    SculptD and Uke like this.