94/90 Hybrid Update - SLOSS

[Pep]

So I hustled up before the bad weather came in and got the bike finished (finished enough to start, test lights, etc.)
The bike started up fine, I revved the engine just a bit and as I cut the throttle, she died. No more spark.
The engine had big, fat spark the other day (key on, nice spark; key off, no spark).
I checked the timing and all connections, fuse looks fine, swapped plugs, but still no spark.
I have not yet learned how to test the lighting and exciting coils on the stator (though I think that’s coming…).
But I did test the primary ignition coil - the primary winding resistance test (black wire to blue wire) looked good - 1.9 ohms. But I got nothing on the secondary winding resistance check (spark plug wire to blue wire). I checked some other primary ignition coils in my pile, and could get a reading on both spots.
Is this as simple as cutting the wire and replacing the cap? The cap interior is sparkling clean - no corrosion, and this coil came off a running bike - so not sure if this is a red herring.
Are the exciting/lighting coil tests performed bike side? Or do I need to disassemble the stator and all soldered connections?
Any ideas on a likely culprit for SLOSS (Sudden Loss Of Spark Syndrome)?
Thanks,
Laurie

[rlkarren]

Your symptoms and tests lead me to believe the spark plug wire may be suspect.

On the Ignition coil, if you have nothing between blue wire and plug wire, that tells me there is a break in the wire somewhere in the secondary winding or the plug wire itself. I think it would be OK to try a test light between blue and plug wire. If it lights, it's OK, if not, there's definitely sometime wrong.

My next step would be to try a "known good" coil. But, I would also make sure all the lighting coils are disconnected so that the test consists of only the ignition circuits. To do that, all you need to do is connect only the black wire to the key switch, make sure the others do not ground out. The black wire is the ignition ground wire. Grounding it will kill the motor.

If that still doesn't work, I would look at the exciting coil next. I would use all 3 tests in the manual; Continuity, Short-to-core, and resistance. The exciting coil should be generating some current, (don't know how much though), and I'm guessing if try placing a voltmeter between the black and blue, (or ground), that go to the ignition and have someone kick it over. You should get something out of that.

You can do the coil tests without removing the flywheel. Using the wires that go to the keyswitch, the green wire to blue wire will test one light coil, the yellow wire to blue wire will test both light coils together. The blue and black wire to the ignition will test the exciting coil. If tests pass using these wire connections, I see no reason to tear it down.

Anyway, those are my thoughts off the top of my head.

Roger

[Bruce Young]

Hello, Burr- Texas; one other simple issue that can happen when you pull the spark plug cap off the Plug, if its some models there is a spring inside that will pull out a little and then when put back on will not make proper connection. This is especially true on Magura and early NGK type spark plug caps. Just a thought. Since it did run and now no spark.

The other test,s suggested are more time, start with the most simple first. and then as you know the process of elimation. Bruce
Hodakaparts.com Idaho.

[Pep]

Thanks Roger and Bruce. Like y'all said, initial findings point to a bad primary ignition coil.
I have a drawer full of coils, but no way to ID them (the Super Rats are pretty obvious) - but I can't seem to make sense of the codes printed on them - if there's a way to tell, I'd love to know.
I pulled the spark plug cap off the wire (it is the coil and tang type) the tang was rusty, corroded and ready to snap.
I tested between the blue wire and exposed spark wire - tested fine
So it looks like problem number one is a bad connection at the cap (problem number two is not having any spares!).
Hopefully this solves the SLOSS crisis. If not, Roger, your other tips will come in handy for further diagnostics.
Many thanks guys for all the quick help.
P.S
Here's a peek at the bike (not quite finished), but getting close.

[Bruce Young]

Hello Texas, Coil Mtg. Does your frame have two small tabs to mount the coil to the frame, and is the coil grey in color, and about 4" long. Thats an ACE 90 coil.

Other type of coil is light grey blue in color and about 5" in length and the mount is just one longer tab. Eather way the coils would interchange, Check for OEM count.

Bad coil is somthing that happens all the time. Bad grounds, bad contact, not very good coils and old, age add to their failing.

Good luck

[Pep]

Hi Bruce, I thought the Ace 90 coils were case-mounted, and the small tab on the frame is for a horn?
This bike has a 94 ignition system - I figured that a 100cc coil would not interchange with a 125?

[rlkarren]

If it were me...

I would try an Ace 100 Coil if that's what I had. (As long as we're talking about the coil that mounts under the tank and not the exciting coil. The exciting coil is definitely different and wouldn't work). For the Ignition coil under the tank, the part numbers are only distinguishable by null, A, or C, i.e. 923008, 923008A and 923008C, which indicates to me that there were no significant changes between the three.

But, I am prepared to be corrected by someone with more knowledge/experience.

Roger

[Pep]

Thanks Roger, I had no idea those coils were interchangeable - particularly between an Ace and Wombat. A Super Rat coil would be great (mounts with no tabs).
I might give this a try.

[Pep]

Ok folks - snow here in Central Texas (official freak-out weather for us locals) - a time to stay home, eat chili, and clean your guns.
Anyway, I mounted a good Dirt Squirt coil on the bike - spark has returned.
I fired the bike up and the horn, brake lights, and headlights all work perfectly! That new headlight is way brighter!
Roger, Dale, and Brian - thank you SO MUCH for all the wiring help. I basically followed Roger's new wiring diagram (using the regulator and 15 amp fuse).
So this bike has a 94 engine and stator, (at the moment, a 96 primary ignition coil), wired into an Ace 90 harness - I swapped the headlight (based on Roger's find) for a new version (called: 5-3/4" MOTORCYCLE 6V HALOGEN H4 HEADLIGHT 6 VOLT 35/35W - about $30 on eBay). The light was a near-perfect fit in the bucket (just a teeny bit of grinding needed on the inner rim).
She sounded great, but I have a leaky float bowl to address - as an aside, this bowl has a little flange mechanism mounted on the side (source of the leak). It looks like a shortcut way to drain your carb - I'm curious - was this something that came on some Mikunis or was it an aftermarket modification?
Stay warm,
Laurie

[Dale]

Laurie, Congrats on the wiring, lighting and finding the bad coil. I noted the baby powder on the front tire and then the Michelin Gazelle. I will look forward to your review of this tire. I have them on two bikes now and I like the look, the sizing and the price, but I probably have a combined 15 miles on them.

No clue on your carb bowl. I have never seen anything like that.

And for your bike build... that is quite a combo. Looks like a sleeper to me. Pretty cool.
Dale

[rlkarren]

yeehaw!

You've verified that wiring diagram is correct! Cool! And you've also verified that the coils are basically the same. More good info. I suspected they were. And now you can see for yourself that the halogen headlight is a great replacement option. It certainly burns brighter. I, unfortunately, dropped mine while testing and shattered the lens so I wasn't able to get pictures of it burning on the AC circuit. Since yours burns ONLY on the AC circuit, would you mind posting a photo so everyone can see how bright it is?

Thanks, I feel like I accomplished something, vicariously.

Roger

[Pep]

Thanks Roger and Dale, really appreciate your help on this odd project.
Dale, I mounted the other Gazelle this morning - I too like the look and price - seems like a good choice for a mostly road bike.
Roger, I will get a photo of the light running, maybe a video, if that's possible on the forum.
At the moment, I need to pull the carb, find a spare float bowl (or try a repair on this one) and cut down one of the reed manifold studs (there's a little interference with the length of the stud and the carb body).
And did I mention there's *SNOW* outside?! A person could be killed in this weather !
Here's the bike, a little closer to finished...
-Laurie

[bchappy]

Looks like you are waiting on a set of 50th anniversary tank badges!!

[Pep]

Bill, yes indeed! Waiting on those anniversary badges...
I got the carb patched, so Roger, here are some photos of the light running on the bike - very bright!
This bike has some awesome compression - looking forward to a weekend of test riding/tuning
-Laurie