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Discussion Starter #1
I've dug through most of the electrical issues threads, and learned a lot. But I still have questions pertaining to the CB175 currently torn apart in my garage. You can probably dig up my year-old project thread on it; fixing and selling our old house, plus buying and fixing a new one, has significantly delayed work on the bike.

FRAME GROUND
Hours of troubleshooting my switches eventually showed me that I have lost my frame ground. I know that I can just run some ground wire myself, but I'd like to try to restore the original ground first. I've got ground on the big cable from battery negative to the frame and engine mount bolt. But no ground on the green wires in the headlight shell (or green wire anywhere else, for that matter.) Can someone tell me where the green wires SHOULD be connected to ground? I haven't found it yet.

CONDENSER
I have spark across the points, and spark on the plug. But it's not a very convincing spark, and when I crank the started, I don't get any spark for 3 or 4 revolutions. Before I buy a coil and/or condenser, I want to do what I can to test what I have. I've been testing the condenser, but am not sure how to intepret the results.

Test #1: If I charge it off the battery, then short the condenser positive to the case, I don't get the spark that I'm told to expect. However, if I charge it up then put it on the voltmeter, I can watch it go from 12+ volts down to zero as it discharges across the resistor in the meter.

Test #2: Measuring it on my (admittedly cheap Harbor Freight) digital multimeter, it consistently measures at .32 microfarads. My Clymer manual says to expect .02 to .03 uF. So I'm off by an order of magnitude.

So, to those of you who know more than I do about this--is my condenser bad?

COIL
One of the few tests you can do on the coil is check for open or shorted windings. Measuring across the primary winding would be from the hot ignition-switched wire (black) to the points wire (blue), right? Measuring across the secondary winding(s) would be from a plug wire to --??? The other plug wire? The blue wire? Black wire? Frame ground? I'm not clear on this.

And on the 175 where both plugs fire of a single point, I have TWO secondary windings, don't I? What implications does that have for selection and wiring of a coil from mikesxs?

Thanks in advance for help on this. I know I'd learn a lot by putting it all together and trying to run it, but it hasn't run for me yet, and I'd like to complete the assembly with the best chance of a running bike when I get there. There's kind of a master ignition troubleshooting thread stickied, I know, but it pertains to two-coil (dual points?) bikes, and is different enough to confuse me.

--Mark
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

Let me take a stab at a couple of your questions.

I don't know about the 175 but on the 450 there is a ground wire pig tail that is part of the wiring harness and connects to the battery. You can see it circled in Red on this PDF file. http://bmnellis.com/pics/GroundWire.pdf

As for the "every 3 or 4 revolutions" getting spark. Rather than crank the engine with the starter try this. Turn the motor over until you get to a position where the points are closed. Remove one of the plugs and, with the ignition on, use your finger to manually open the point and see if the plug fires (with the plug grounded to the engine of course). This procedure will not check the condenser but it will verify the primary and secondary ignition system.

Let us know what you come up with.
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

Looked over the bike again with a flashlight; no pigtail revealed itself. Also checked the diagrams in the parts fiche for my year, and previous years--nothing showed up there, either. Is the whole thing maybe grounded through the taillight housing or something goofy like that? Still stumped...

I took the plug caps off, chopped off the wire ends until I saw shiny copper, and was able to get spark to jump to the engine block over nearly 1/4 inch when the points opened. Didn't spark every time I opened them manually, and I don't know if they sparked every time the points opened when I cranked the starter, either.

For now, though, I think I'm going to figure my coil's okay (expensive), my condenser's probably good enough (a little expensive), and just replace the plug caps for now. One of them is gunked up from decaying wire insulation, and they're dirt cheap to add to my order from denniskirk.com.

I'll worry about getting it back together now, and see how my spark is when I actually give it something to burn.
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

I don't have a service manual for the 175 but it should show the ground connection on the wiring diagram.

In the image below is what does the pigtail circled in Red connect to?


http://picasaweb.google.com/6453635/201 ... 6253433682
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

Picture's not coming through for me...all I see is a red "X"
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

Not sure what it's supposed to be as stock - the shop manual diagram doesn't make the ground situation very clear.
So just run a connector from any green wire to the battery negative.
Check the green wires for continuity to ground wherever you see them, you should be good to go.
If you recently painted or powdercoated it sometimes causes ground problems.
Run a ground wire to your handlebars too, in case they're not grounding.....
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

I found that pigtail. It's a green wire, female connector, and the connector insulation is half-green -- unlike anything else on the bike.
[attachment=2:mef488ld]iphone 001.jpg[/attachment:mef488ld]

It was tucked in the rear fender wiring bundle, unconnected.
[attachment=1:mef488ld]iphone 002.jpg[/attachment:mef488ld]

Now I *know* that I had good ground before, even with this wire dangling. So I don't think it's the source of the problem. I think it's the wire in the diagram coming off the ground of the rectifier, like some sort of test point?
[attachment=0:mef488ld]iphone 004.jpg[/attachment:mef488ld]

But even if it's not the source of the problem, it could still be part of the solution. Looks like a good solid ground--anyone see a reason not to just tie into it?
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

I have dealt with the ground problem on cb175's before. I was trying to install the upgraded rectifier from oregon motorcycle parts, and lost the ground completly. It seems that on the cb175, the only ground for the wiring harness is the bolt where the rectifier bolts to the frame, up under the seat area. That seems to ground the whole system to the frame. If that is isolated somehow, you're gonna be dead in the water. How this helps you.
Larry
 

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Re: Lost my frame ground, and is my condenser bad? (1971 CB1

The MAIN ground is from the battery negative terminal to the engine mount bolt (and hence to the frame) These contact points should be BARE metal.... Often a frame repaint (or worse, powdercoat) will accidently remove this chassis ground... It should be reinstated by grinding/sanding to bare metal again...
 
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