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Thread: 1980 GS850 Rebuild

  1. #1
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    Default 1980 GS850 Rebuild

    Hello GS Forum. I got my hands on a non-running GS a couple of months ago CHEAP, so I'm slowly working my way through it in an effort to get it back on the road. It has a fair oil leak somewhere (I think toward the top end, TBD), and the wiring is pretty hacked up. I'm taking it slow and trying not to spend too much money in case it turns out to be a lost cause. Here's my progress so far:

    I removed the Vetter fairing. It won't be going back on. Also removed the tank (remarkably clean and rust free inside), seat, airbox and carbs so I could give the bike a thorough degreasing.

    Now that it's clean enough to touch, I started working through the wiring. The PO had installed a new generator, but he told me it still wasn't charging. I disconnected and cleaned all the wiring harness connectors, labeled everything and temporarily reconnected the hacked wires so I could do some testing on the electrical system and the engine.

    I temporarily connected one of my jet ski batteries and was able to confirm that the engine turns over. One small victory! So, I shot a little oil in each cylinder and checked compression. Compression in all four holes was good, so I think it's safe to start spending a little money on this thing.

    I disassembled the carbs, cleaned them up, adjusted floats and replaced o-rings. Carbs, like the gas tank were cleaner than I expected and in overall pretty good condition. I reinstalled the carbs and hooked up an auxiliary fuel tank, cleaned the plugs, topped off the oil and tried to start it. It took a little spinning, but eventually fired up!! It was loaded up initially because of the oil I'd put in the cylinders, but it eventually cleaned out and ran pretty good. I hadn't installed the air box, so it liked to stumble through mid range, but it would rev out and it idles well. It also shifts through all the gears like it should. I had identified some mistakes the PO had made wiring up the new generator, so it's now charging as well. Victory #2. Time to spend more money.

    My next step is to get it reassembled far enough to do some road testing and hopefully find out where the oil leak is. So, I purchased a new battery and have the rubber pipes between the air box and carburetors on order (~$85! Ouch, but the old ones were rock hard). I also bought a used headlight (couldn't mount the one from the Vetter) and cleaned up the brake systems. I ended up needing a rebuild kit for the front master cylinder, so that's on order. Finally, I reworked my temporary wire connections to a more permanent state. I tried to restart, but now I'm getting no spark at any of the plugs. I'm working my way back through my wiring, but haven't found the culprit yet. I did find that someone had installed an aftermarket signal generator at some point (bonus!?). I was hoping to post a picture so I could get help identifying the manufacturer, but the site will only let me attached on file. Maybe I'll follow up later.

    So, here's my first real question to the GS experts. In trouble shooting my no spark situation, I'm finding good voltage (bright light on my test light) at the orange/white wires to the coils with the ignition switch turned on. I'm getting a very dim light at the black and white coil wires with the ignition on. When I run the starter, the dim light kind of flickers. I guess I was expecting something a little more dramatic. Is this typical of a non-points ignition system? Is my signal generator not getting adequate voltage? The service manual only addressed points, so I'm not sure what to investigate next.

    Thanks in advance for your help. I'll continue to update, and I'll post more pictures when I have something worth showing off.

    2020-09-11 18.50.21.jpg
    1980 Suzuki GS850GT
    2011 Ducati Multistrada 1200
    1993 Honda XR650L

  2. #2
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    Default

    Here's a picture of the signal generator. If anyone knows the manufacturer or can provide any other information, I'd appreciate it. Thanks.

    2020-10-20 17.44.41.jpg
    1980 Suzuki GS850GT
    2011 Ducati Multistrada 1200
    1993 Honda XR650L

  3. #3
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    Default

    One more shot of the bike before the initial disassembly. Sorry for posting out of order.

    00X0X_9MnfJwsvwfi_0t20lM_1200x900.jpg
    1980 Suzuki GS850GT
    2011 Ducati Multistrada 1200
    1993 Honda XR650L

  4. #4
    salty_monk's Avatar
    salty_monk is offline Forum LongTimer GSResource Superstar
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    Default

    Welcome to the forum! It’s usually the CDI that goes out (spark box) not the signal generator. The Dyna ignition fits that bike and is worthwhile for peace of mind in my book....

    How are the brakes? The Twinpot brakes fit that bike... at the very least you should flush all the calipers out and change the lines for new braided ones. Safety first....

    Cheers,

    Dan

    1980 GS1000G - Sold
    1978 GS1000E - Finished!
    1980 GS550E - Fixed & given to a friend
    1983 GS750ES Special - Sold
    2009 KLR 650 - Sold - gone to TX!
    1982 GS1100G - Rebuilt and finished. - Sold

    www.agadisplay.com
    www.parasiticsanalytics.com

    TWINPOT BRAKE UPGRADE LINKY: http://www.thegsresources.com/_forum...e-on-78-Skunk/

  5. #5
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    Although it is often mis-labeled as "CDI", you don't have an actual CDI on your bike.

    There is no large capacitor that gets discharged to provide the spark, hence no "Capacitor Discharge Ignition".

    What you DO have is a box of transistors that act like the mechanical points, Suzuki calls it the "Ignitor". You should always see a strong voltage (should be VERY close to battery voltage) on the orange/white wire. The wires at the other end of the coils are effectively switched ground wires, so they WILL flicker.

    Won't help your "no spark" situation, but have you checked your valve clearances? That is a MUST DO item for any bike where you don't know the history.

    .

    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
    #2 son: 1980 GS1000G
    Family Portrait
    Siblings and Spouses
    Mom's first ride
    Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
    (Click on my username in the upper-left corner for e-mail info.)

  6. #6
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    Thanks for the input fellas. I'll continue to sort the wiring this weekend. I'm suspecting a bad ground, but who knows. My master cylinder rebuild kit showed up, so that's what I worked on yesterday. Good brakes all the way around now.

    Valve adjustment is definitely on the to-do list. I expect to have to replace some gaskets (maybe even the base gasket) before this is all over with, so the engine is probably coming out at some point. That seems like the most convenient time to deal with valves.
    1980 Suzuki GS850GT
    2011 Ducati Multistrada 1200
    1993 Honda XR650L

  7. #7
    Join Date
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    Location
    Montreal Quebec
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    Default

    Hi there!

    Welcome in!

    I strongly believe all you'll ever need is in there: http://gsarchive.bwringer.com/
    Incredibly complete info on your bike.

    For your electrical problem, I'd check the coils first... --> http://gsarchive.bwringer.com/storag...dd-n-ends.html
    Then check if the black wires are getting to ground with the right timing. See the section Testing The Ignition System in the above document.
    Also worth mentionning is connections, of course. Most of my problems dispeared after a through out cleaning of the connectors.

    Good luck...

    Frank
    ------ Current rides: -----------------

    Honda CT70 K0 1970 complete restoration in progress
    Suzuki GS850 1979 as stock as could be... well except for the bars!
    Yamaha FJ-09 2016 with OEM saddle bags for long distance running and gunning
    Yamaha VStar 1300 2007 (wife's) for relaxing

  8. #8
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    Thanks Frank. A well thought out, step by step procedure is invaluable. I knew about BikeCliff's site, but hadn't drilled down that deep.
    1980 Suzuki GS850GT
    2011 Ducati Multistrada 1200
    1993 Honda XR650L

  9. #9
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    Quote Originally Posted by twerth View Post
    I expect to have to replace some gaskets (maybe even the base gasket) before this is all over with, so the engine is probably coming out at some point.
    There is no need to remove the engine to replace the base gasket. In fact, unless you have a way to stabilize the engine on a bench or a dedicated engine stand, I think it would be easier to replace the gasket while the engine is still in the frame. Everything necessary comes off easily enough in the frame. I have just replaced an engine in my 850 and can confirm this from experience, not just guessing.

    .

    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
    #2 son: 1980 GS1000G
    Family Portrait
    Siblings and Spouses
    Mom's first ride
    Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
    (Click on my username in the upper-left corner for e-mail info.)

  10. #10
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    Sep 2020
    Location
    Parkville, MO
    Posts
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    Quote Originally Posted by Steve View Post
    There is no need to remove the engine to replace the base gasket. In fact, unless you have a way to stabilize the engine on a bench or a dedicated engine stand, I think it would be easier to replace the gasket while the engine is still in the frame. Everything necessary comes off easily enough in the frame. I have just replaced an engine in my 850 and can confirm this from experience, not just guessing.

    .
    Good to know. But, I've got more than one reason to remove the engine. PO had "murdered" it out, so I want to disassemble as far as I can to get this thing cleaned up. I'm not afraid to drop an engine. Here's a shot of my Multi a couple of months ago when it had a crank bearing go bad.

    2020-08-11 19.10.12.jpg
    1980 Suzuki GS850GT
    2011 Ducati Multistrada 1200
    1993 Honda XR650L

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