possibly bad coils, caused by bad tci?

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Mr. Matt
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Joined: Wed May 25, 2016 10:17 pm

possibly bad coils, caused by bad tci?

Post by Mr. Matt »

So i had one of those great ideas to try and fix something that wasn't broken...... now its broken :duh: here is the story

Bike ran good before, kinda had a hiccup at 3grand and a weird idle, had been telling myself to reshim valves so I finally talked myself into it

Tried adjusting valve clearances, exhaust side was tight, intake was fine, reshimmed now all are within spec
Upon re-assembling realized my battery was never disconnected, battery was shit anyways, assumed all is well
Tried to fire for first time, engine sounded better cranking but never started
Start tracing around for a forgotten connector possibly that wasn't hooked up, no luck
Check fuses, blah blah everything appears to be fine, also purchased and installed new battery at this time
Still no start
Go through Don's "Now What" thread, everything test out fine (stator, coils, safety circuit, everything in the thread,) but no spark to be found
Eventually upon a suggestion of using the header bolt as a ground rather than the head, I was able to see a little glimmer of spark
Hooked all back up to fire it up, still no luck
So a few weeks pass and I want to ride worse than ever
Pull valve cover back off to verify shim accuracy and timing, all within spec and timing seems to be lined up by split in casing to the lobes and dimples on cams
Check on the bike, no spark still, check safety circuit for continuity, checked ok but has high resistance attributed to kickstand switch, so I bypassed it now has lower resistance (50+ ohms down to 2-3)
Now going through Dons "Now What" thread again, I checked the secondary resistance on the coils as 36k ohms now, primary as 2.5ish ohms, both out of spec, secondary by 3x spec (12k ohms)

I had always thought i may have messed up something since I stupidly forgot to disconnect the battery, could I have fried the TCI? If the TCI is fried would it have taken out my coils as well?? I want to rip it apart the TCI to get a visual if any burnt traces, or drives or whatever magic stuff contained within looks burnt. Anyone know how to rip into these, or have suggestions as to how I can get back on two wheels without having to steal my daughters bicycle?? Its pink but i will do it dammit.
DonTZ125
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Re: possibly bad coils, caused by bad tci?

Post by DonTZ125 »

Soaking the TCI in acetone for a day or so will dissolve the protective coating that also acts as a glue to keep the header & board in the box - it slides in and out like a drawer.

Unplug the coil primary leads at the coils. Test for continuity across the orange wire to ground, and the grey wire to ground. You should read open circuit. The only way I can think of that a damaged TCI could damage a coil would be to allow excess dwell, allowing it to overcharge and overheat. Far more likely is a damaged VRR causing an overvoltage situation.

When you test the secondary resistance, did you remove the plug caps? A failing plug cap resistor (ie shattering to pieces inside the cap) does nothing to help.
Mr. Matt
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Posts: 6
Joined: Wed May 25, 2016 10:17 pm

Re: possibly bad coils, caused by bad tci?

Post by Mr. Matt »

sweet, gonna go buy some acetone. should i fully submerge it in the acetone? (probably gonna wait on this until making sure coils are either good or not)

testing the coils at the soldered connections to ground, i was getting continuity at both solders, on both coils if memory serves me correct but after taking readings for an hour or so, everything blurs together.
and no, i did not remove the spark plug boots when checking the secondary resistance, now upon reading more i guess i should have?

I am currently "working" lol, and will perform more test when i get home and get back with you.

thanks alot, i am a self taught shade tree "mechanic" and need some help, so i do truly appreciate it
Br1zzy
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Re: possibly bad coils, caused by bad tci?

Post by Br1zzy »

Did you ever get it running?
Mr. Matt
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Posts: 6
Joined: Wed May 25, 2016 10:17 pm

Re: possibly bad coils, caused by bad tci?

Post by Mr. Matt »

no never did. i think it may be tci but haven't messed with it in so long. gonna have to get back on it once the weather cools off for me.
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