Checking coils, got a shock!

[Guest]

I clipped back my spark plug wires about .5" because the exposed copper was either corroded or not exposed. When I was clipping the third wire, I got a shock and heard the familiar electronic spark.

Reluctantly I continued on and didn't get any more shocks. I've hooked the leads of my multimeter up to wires 1 & 2 and then 3 & 4, but I'm getting no reading.

Should the multimeter still be set to ohms? Should the ignition be on? What am I doing wrong?

BTW - I was getting no reading before the shock too. I tested the multimeter on my battery and I'm getting a reading there just fine.

Thanks,
~Mike

[t3rmin]

It would probably be possible to get a shock when clipping the wires if the rotor happened to be aligned with the pickup coil for that cylinder and the ignition were on. Actually the potential for shockage in that scenario would be on two wires, since it's a wasted-spark ignition.

Whether you actually got a shock (assuming the rotor was aligned) would depend on how/if your body/the cutters were grounded. I don't think it's anything to worry about as far as whether something is messed up. The ignition is designed to spark. ;-)

If you clipped .5", though, you probably clipped too much. Typically clipping off just a sliver (1/4" - 1/8") is enough to get good wire exposed. But as long as your wires are still long enough to reach, you're fine.

*EDIT* I think I'm backwards. On these bikes there is always power to the coils. You get a spark when the ground is interrupted. So you could probably get a shock/spark out of any of the wires if you fiddled with them enough with the ignition on.

[UncleMike]

It would probably be possible to get a shock when clipping the wires if the rotor happened to be aligned with the pickup coil for that cylinder and the ignition were on. Actually the potential for shockage in that scenario would be on two wires, since it's a wasted-spark ignition.

Whether you actually got a shock (assuming the rotor was aligned) would depend on how/if your body/the cutters were grounded. I don't think it's anything to worry about as far as whether something is messed up. The ignition is designed to spark. ;-)

If you clipped .5", though, you probably clipped too much. Typically clipping off just a sliver (1/4" - 1/8") is enough to get good wire exposed. But as long as your wires are still long enough to reach, you're fine.

*EDIT* I think I'm backwards. On these bikes there is always power to the coils. You get a spark when the ground is interrupted. So you could probably get a shock/spark out of any of the wires if you fiddled with them enough with the ignition on.

Ignition was off and I wasn't clipping at the time, was just reaching for the other wire.

Actually, I clipped off closer to .25" in retrospect. I was just throwing a number out there. They're still plenty long.

I'm just wondering if perhaps my wires might be bad, leading to the spark.

~Mike

[t3rmin]

Ignition was off and I wasn't clipping at the time, was just reaching for the other wire.

Actually, I clipped off closer to .25" in retrospect. I was just throwing a number out there. They're still plenty long.

I'm just wondering if perhaps my wires might be bad, leading to the spark.

~Mike

Hmm... perhaps coils can hold a charge (like a capacitor) for a little while, and then release it through your body to ground when touched. Not sure if that's possible, though.

Make sure you don't have voltage to the coils when the ignition is off. Perhaps a PO wired the coils directly to the battery so they're getting power all of the time? That would cause your battery to run down and probably fry the coils eventually. I had inadequate voltage to the coils so I wired them directly to the battery, but with a relay in between so there's only power when the ignition is on (per some GREAT advice on these forums).

*EDIT* You can check for voltage at the coils by putting the red multimeter lead on the contact of the orange wire on one coil and the black multimeter lead on the negative battery terminal. Then switch the red multimeter lead to the other orange wire to check the other coil. You should have 12+v with ignition on and nothing with ignition off. (switch your multimeter to DC 20v scale).

[UncleMike]

I can't tell you how much I appreciate you telling me every step in checking things like this. It's really what I need as I have zero experience with most of this stuff, and too often I run into what people assume is step-by-step, but still gets lost on me.

Thanks,
~Mike

[t3rmin]

No prob. Let me know what you find out; I'm kind of intrigued now.

[UncleMike]

No prob. Let me know what you find out; I'm kind of intrigued now.

1 & 4 - 11.53, measured at 20K
2 & 3 - 12.15, measured at 20K

That's checking resistance with the caps off, straight from the wires.

[t3rmin]

Actually you don't want to be checking resistance, you need to see how many volts you've got at the coils. Switch your meter to 20 volt DC and check again.

Also, make sure to test it both with the ignition off and with the ignition on.

And I'm not talking about the spark plug wires, I'm talking about the wires that feed voltage to the coils. You'll have to take the tank off. It should be an orange wire.

[UncleMike]

Actually you don't want to be checking resistance, you need to see how many volts you've got at the coils. Switch your meter to 20 volt DC and check again.

Also, make sure to test it both with the ignition off and with the ignition on.

And I'm not talking about the spark plug wires, I'm talking about the wires that feed voltage to the coils. You'll have to take the tank off. It should be an orange wire.

Sure thing, that's up next. The original intention of this grand adventure was first to check the resistance. I'm trying to rule out EVERYTHING step by step.

[Billy Ricks]

Mike, don't you know the way to check coils is to pi$$ on it while someone cranks the engine?

You should get 3-5 ohms on the primary side of the primary side of the coils and if they are stockers 30k-50k on the secondary sides using leads from 1 & 4 then 2 & 3. If they are Dyna or Accel coils 20k-30k is what you should get.

[UncleMike]

Mike, don't you know the way to check coils is to pi$$ on it while someone cranks the engine?

You should get 3-5 ohms on the primary side of the primary side of the coils and if they are stockers 30k-50k on the secondary sides using leads from 1 & 4 then 2 & 3. If they are Dyna or Accel coils 20k-30k is what you should get.

So, did those numbers look okay for the coils that I got?

11.53 and 12.15 at 20K. The math on this mystifies me.

[t3rmin]

At a 20K scale, 11.53 is 11.54kOhms and 12.15 is 12.15KOhms. So you're a bit low I guess.

[UncleMike]

At a 20K scale, 11.53 is 11.54kOhms and 12.15 is 12.15KOhms. So you're a bit low I guess.

Great. One more freakin' thing. What do I expect for a $100 bike. At least she's pretty and I'm learning a lot.

[t3rmin]

I've got you beat I think. I paid $400 for mine, thinking it only needed a new coil. Now I'm in probably $1200 total.

[UncleMike]

I've got you beat I think. I paid $400 for mine, thinking it only needed a new coil. Now I'm in probably $1200 total.

You're right. You win.