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Discussion Starter · #1 ·
So, a couple months ago I was out riding my 1979 cm400a, not a care in the world. Parked it at home for a couple hours, then hopped back on to go out. It cranked and cranked and cranked but no start.

Next day, I checked out the Killswitch pod, found nothing amiss. Pulled the spark plugs and checked for spark. Nothing.

Disconnected the kickstand switch, cleaned as best I could. Nothing.

Then began a long process of figuring out why there is no spark so suddenly. Replaced plugs, had the mechanic next door help me check the ignition coils, and there was no power coming out! Thought maybe bad coils, so followed all the steps to perform the gm coil mod. Nothing.

Local junkyard had a hondamatic in stock! Picked up a new cdi and change relay. Every combination of old and new relay and cdi yielded no results.

Now: we believe the stator is bad. Will double check my readings when I get home from work, but stator is currently removed from the bike. Can't track down a replacement for the "a" model stator on eBay, and rewind service would be next step. But at 275 bucks I'd rather gaurantee that the stator is the issue.

So, any tips or anyone have this same experience? Or have the same bike and be willing to let me mail in my stator to do a swap-and-check?

Looking to sell it soon, and would rather sell a working and worthwhile bike rather than a project.


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Check the stator readings... Your junkyard cdi could also be bad.
There's a sticky in the electrical section about diagnosing all this. I'd recommend to go through everything and list your numbers.
I think you may be able to swap stator with non A model, but would require additional stuff to make it work. Try a search, or longdistancerider can confirm the specifics.
 

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Discussion Starter · #3 ·
Correction:cdi was an eBay item, with a gaurantee to work caveat. So I'm flush with A model cdis at the moment. Once I confirm both work will probably sell the spare. I'll get readings in a couple hours

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Sorry no way to check the CDI box. The full service manual will tell you the numbers and how to check the stator and other elec parts, Non A models wont work on A model. Also dont forget to check the change switch and relay. A 400T stator will work on the A model if you change the fly wheel and CDI box to the 400T but you will loose the change switch. As stated above there is a sticky in the 400 elec section on this.

Bill
 

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There's a rewinding shop in Alabama that others have recommended, Custom Rewind.
Do you have the FSM and A model supplement?
 

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Discussion Starter · #6 ·
Yes, and a blown up wiring diagram. My multimeter isn't the best but if I read the resistance coming off of the generators correctly, I have no continuity between the three phases, couldn't get an accurate read on the ground though... Backyard mechanic comes home on Tuesday, will run through the proper test procedures at that point once more

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disconnecting the cdi black and white wire effectively disables the ign kill, so try that.

also check/record stator ACV output at cranking with the plugs out, idle ( if it will run ?? ) and at 4k revs, cold and hot.

no acv ( or not enough ) means non runner.

note fro memory, the cdi marked "A" type where unreliable.......
 

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If you unplug the connector with the blue wire and a white wire coming from your stator , connect your multi meter and set it for ac voltage,crank your engine over,you need 10 volts or greater if not your stator is bad. let us know what you get.
 
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