1980 GS850 Rebuild

[twerth]

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

[twerth]

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

[twerth]

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

00X0X_9MnfJwsvwfi_0t20lM_1200x900.jpg

[salty_monk]

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

[Steve]

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.

.

[twerth]

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.

[maisf]

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

[twerth]

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.

[Steve]

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.

.

[twerth]

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

[Steve]

The technique that my son and I used to change my engine works rather well. It does require two people without major physical handicaps.

After removing everything that holds the engine to the bike (carbs, exhaust, wiring, mounts, etc.) the engine is just sitting on the frame. We used two ratchet straps as lifting slings. On the left side, the only practical attachment (on an 850) is the left rear, above the shifter. There is a hole where the airbox drain hose goes through. Place one hook there and hook the second hook of the same strap into the first hook. Loop the strap around the stator cover, then up, over your neck. The second strap can be hooked into holes in the crankcase that appear to be designed for this. One is in the front, one is at the rear. Place this strap over the second person's neck. Adjust the length of the straps so you are standing almost upright, but can still see the engine. Use your legs to lift and swing the engine to the right side a bit. You will have to move the left-side strap/sling to inside the frame rails while balancing the engine on the right frame rail, then move it again with the strap to the right of the frame and set the engine down on a dolly.

It probably sounds a bit harder than it actually is, but the two of us were able to easily remove the engine from my bike, then remove the engine from the parts bike and move it to my bike. One of the smaller Harbor Freight dollies will hold the engine well enough and it's easy to push around on the floor.

.

[jsandidge]

The technique that my son and I used to change my engine works rather well. It does require two people without major physical handicaps.

After removing everything that holds the engine to the bike (carbs, exhaust, wiring, mounts, etc.) the engine is just sitting on the frame. We used two ratchet straps as lifting slings. On the left side, the only practical attachment (on an 850) is the left rear, above the shifter. There is a hole where the airbox drain hose goes through. Place one hook there and hook the second hook of the same strap into the first hook. Loop the strap around the stator cover, then up, over your neck. The second strap can be hooked into holes in the crankcase that appear to be designed for this. One is in the front, one is at the rear. Place this strap over the second person's neck. Adjust the length of the straps so you are standing almost upright, but can still see the engine. Use your legs to lift and swing the engine to the right side a bit. You will have to move the left-side strap/sling to inside the frame rails while balancing the engine on the right frame rail, then move it again with the strap to the right of the frame and set the engine down on a dolly.

It probably sounds a bit harder than it actually is, but the two of us were able to easily remove the engine from my bike, then remove the engine from the parts bike and move it to my bike. One of the smaller Harbor Freight dollies will hold the engine well enough and it's easy to push around on the floor.

.

Wow, I wish you had that on video.

[twerth]

Got it running. The chassis ground for the wiring harness was almost nonexistent. I added a new ground wire from the harness ground directly to the engine and all is good. It fired right up. I don't have a headlight or tail lights, so there are still some electrical gremlins to figure out. I also installed the airbox, and it's evident that I need to spend some more time with the carbs.

That's ok though because I'm still a couple of weeks from being able to ride it (I'm on crutches at the moment). I'll keep chipping away and hopefully I'll have more progress to report by next weekend. With a little luck it'll be close to ready for a shakedown cruise.

[Steve]

Wow, I wish you had that on video.

Me, too, but we were both rather busy at the time.

We might be talked into placing the (now)spare engine back into the parts bike, just for the video.

.

[jsandidge]

Me, too, but we were both rather busy at the time.

We might be talked into placing the (now)spare engine back into the parts bike, just for the video.

.

Please do. I've seen videos of several other methods. This one sounds much more interesting.