NX650 Electrical Gremlin

[Mr. Green Genes]

1989 model, said to be the same engine as an XR.

The bike electrical (spark - lights still good) will cut off as if I hit the kill switch. It is an intermittent problem and I can cycle the kill switch and the problem goes away. I have cleaned & dielectric greased every plug & terminal on the bike. Cleaned and greased the kill switch. Afterwards, put 100 miles on it Saturday without seeing the problem, but it came back this evening.

The battery holds up through however many crank cycles are required to get it started, but I wonder if there might be an internal short or open which is tripping up & shutting down the CDI unit?

Does this sound like a familiar XR problem to anyone out there?

 

[Moekazi]

Sadly, i'm just gonna have to fling wacky stuff at you.

Did you check the soldering when you had the kill switch apart? I've seen cold soldered wires come loose and cause intermittent problems. It's easy to overlook unless you're looking right at the soldered joint when you move the wires.

I had a Triumph and they had put a crimp connection inside the wiring from the hand controls to the plug. I couldn't see it at all because it was covered by one long continuous piece of sheathing. The wire at the crimp connection broke, but i had intermittent starting problems until in the mean time. It's a long, long shot, but i'd be curious if Honda did something similar.

Either way, take the hand control off. Start the bike and wiggle, pull, and twist it around to see if the bike shuts off. If you have a continuity tester, you can leave the hand control on and jack into the kill switch circuit via the plug.

Someone else with a Triumph had a bike that was shutting off because of a cold solder joint in the ignition switch. Start the bike and see if wiggling the wires to the switch does anything.

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[RollingJ]

These Honda CDIs are known problems. It's a cold solder issue inside the CDI on late 80s /early 90s models. When it dies, if your tach will only jump once when you push the starter and then flatline as you continue to crank, it is the CDI for sure. It happened to my 89 NX250,

 

[Mr. Green Genes]

Up-Date

I am having a hard time accepting that the CDI would continue to malfunction in this manner without progressing to total failure, but it may be the next part I buy.

So far, in addition to the previously mentioned, I have..
Bypassed the kill switch
Bypassed the neutral safety lockout
Cut out the ignition switch plug and soldered the connections and included a toggle switch to bypass the ignition
bought a new battery.

With each new "FIX" the problem goes away for a little while, maybe a 100 miles or so, and then comes back.

Only about 3 places left to look. The CDI, the pulse generator or the stator. Or some fault in the wiring harness.

I think the CDI will be next, but I am still having a hard time with why it hasn't cratered completely. I have added ~1000 miles since this problem started.

Still open for suggestions(?)

 

[Moekazi]

As long as you're bypassing switches... you missed the kickstand switch.

Curious why you think it's killing the spark. I had a GS500 that would just flat die at random times. I'd coast to a safe spot, and it'd fire right back up again. Turned out to be a carburetor problem.
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[Mr. Green Genes]

Well, I finally broke down, bit the bullet and bought a new CDI ($118 fm. Cheap Cycle Parts). 300 miles later, I think it's fixed.

So, if you find yourself having to periodically re-boot your Honda like an old TRS-80, it's probably the CDI.