Bizarre ignition missing in one cylinder

[MisterCinders]

Hello GSR pals. I've run into an ignition hiccup that defies logic.

After running like a champ for quite some time, I ran into sputtering and lurching about an hour into a ride. That it went from smooth to crap instantly made me look to electrical problems, since air/fuel/compression don't typically fail so abruptly.

Limped home on 2 or 3 cylinders and started checking things out.

Battery voltage is solid 13.5v. Coil voltage was spotty then went kaput in the garage. The relay fuse blew.

Changed out the fuse and she'd start and idle. Take her around the block and I can feel it missing under load. Strangely, it seems to not want to fire on Cylinder 4, while Cylinder 1 is good to go.

Checked coils (Dyna Greens installed last year). Resistances check out.

Worried that the relay failed, I swapped the connections to return to the stock wiring. She seemed to idle better, but another trip around the block showed the same missing cylinder.

The No. 4 header gets hot, but not nearly as hot as 1-3. So it's missing but not dead.

Hooked up a colortune to watch the spark in that cylinder, and it definitely comes through spotty.

So I trimmed a bit from the end of the plug lead and swapped the plugs around. Still not better.

Checked voltage at the coils, and there was a pretty significant drop (13v at battery but 8-9v at coils). So I picked up a new relay and wiring and completely rewired the coil relay.

With fresh clean wiring and fully charged battery, I get closer to 11v at the coils. Still a drop, but much better. She started and idled well in garage, so around the block we go. The bike pulled pretty well, but still occasionally pops through the pods and stutters like a missed cylinder. Not a steady and solid power loss (like a failed coil or ignition pick up) from dropping 2 cylinders.

Also, I checked the ignition timing and it's spot on.

The carbs are clean, and when No. 4 fires it shows bright bunson blue. Compression is solid and even across all four. Valves adjusted less than 1,000 miles back.

So what the hell? At this point I cannot figure out what else would disrupt the ignition to affect the one cylinder. Today, I'll check the wiring up front to see if there is something that might be disrupting the power feed to the relay itself (loose wire in headlight bucket?). Otherwise, I am out of ideas.

[chef1366]

I had the same symptons with a bad Dyna S. Call Dynatek and ask how to test it. I can't remember.

[MisterCinders]

I had the same symptons with a bad Dyna S. Call Dynatek and ask how to test it. I can't remember.

I tested the Dyna when checking timing. It's a new unit because my old one failed a few months ago. So I worried that might be the problem, but it checked out.

[posplayr]

Hello GSR pals. I've run into an ignition hiccup that defies logic.

After running like a champ for quite some time, I ran into sputtering and lurching about an hour into a ride. That it went from smooth to crap instantly made me look to electrical problems, since air/fuel/compression don't typically fail so abruptly.

Limped home on 2 or 3 cylinders and started checking things out.

Battery voltage is solid 13.5v. Coil voltage was spotty then went kaput in the garage. The relay fuse blew.

Changed out the fuse and she'd start and idle. Take her around the block and I can feel it missing under load. Strangely, it seems to not want to fire on Cylinder 4, while Cylinder 1 is good to go.

Checked coils (Dyna Greens installed last year). Resistances check out.

Worried that the relay failed, I swapped the connections to return to the stock wiring. She seemed to idle better, but another trip around the block showed the same missing cylinder.

The No. 4 header gets hot, but not nearly as hot as 1-3. So it's missing but not dead.

Hooked up a colortune to watch the spark in that cylinder, and it definitely comes through spotty.

So I trimmed a bit from the end of the plug lead and swapped the plugs around. Still not better.

Checked voltage at the coils, and there was a pretty significant drop (13v at battery but 8-9v at coils). So I picked up a new relay and wiring and completely rewired the coil relay.

With fresh clean wiring and fully charged battery, I get closer to 11v at the coils. Still a drop, but much better. She started and idled well in garage, so around the block we go. The bike pulled pretty well, but still occasionally pops through the pods and stutters like a missed cylinder. Not a steady and solid power loss (like a failed coil or ignition pick up) from dropping 2 cylinders.

Also, I checked the ignition timing and it's spot on.

The carbs are clean, and when No. 4 fires it shows bright bunson blue. Compression is solid and even across all four. Valves adjusted less than 1,000 miles back.

So what the hell? At this point I cannot figure out what else would disrupt the ignition to affect the one cylinder. Today, I'll check the wiring up front to see if there is something that might be disrupting the power feed to the relay itself (loose wire in headlight bucket?). Otherwise, I am out of ideas.

How do you drop 2 volts or more with a coil relay mod? Where are the drops occurring? If your wiring checks out I is possible for a winding to be shorted inside of the coil.

The DynaS could be a problem but not sure how it would create these symptoms especially blowing the relay fuse. What size was it?

I would want to check the coils. Did you use an ohm meter to check both to see they are the same resistance?
EDIT: I see you checked the resistance. HUM

I suspect the coils is shorting once hot. Once way to stress test the coils is to put them in series with each other (an in line fuse might also be wise) and put them across a strong battery (No DynaS or anything else) even a charger to keep the voltage high.

The mid point should be 1/2 of the +12V supply. If one of them shorts that voltage will move either up or down. If it moves up then the upper coil is shorted. If it moves don the lower is shorting.

This should be relatively safe as it will actually put less peak current through your coils than when they are operating but it will be on 100% of the time so on average it will be like operating. Monitor the coils heating up and looking for teh voltage change.

[MisterCinders]

How do you drop 2 volts or more with a coil relay mod? Where are the drops occurring? If your wiring checks out I is possible for a winding to be shorted inside of the coil.

The DynaS could be a problem but not sure how it would create these symptoms especially blowing the relay fuse. What size was it?

I would want to check the coils. Did you use an ohm meter to check both to see they are the same resistance?
EDIT: I see you checked the resistance. HUM

I suspect the coils is shorting once hot. Once way to stress test the coils is to put them in series with each other (an in line fuse might also be wise) and put them across a strong battery (No DynaS or anything else) even a charger to keep the voltage high.

The mid point should be 1/2 of the +12V supply. If one of them shorts that voltage will move either up or down. If it moves up then the upper coil is shorted. If it moves don the lower is shorting.

This should be relatively safe as it will actually put less peak current through your coils than when they are operating but it will be on 100% of the time so on average it will be like operating. Monitor the coils heating up and looking for teh voltage change.

The relay has a 15amp fuse. It hasn't blown again since I re-wired it. I'm going to pull apart the wiring again and double check the voltage across the coils. No super confident in those readings since lining up the meter tips gets a bit fiddly.

Can you clarify that stress test? I think you mean to run them like so:

BATT (+) --fuse-- (+)coil(-) - - - (+)coil(-) -- (-)BATT

Is that correct? For the charger, would that be in place of the battery or to buttress the battery charge?

Thanks.

[posplayr]

.

Can you clarify that stress test? I think you mean to run them like so:

BATT (+) --fuse-- (+)coil(-) - - - (+)coil(-) -- (-)BATT

Is that correct? For the charger, would that be in place of the battery or to buttress the battery charge?

Thanks.

Yes that is all correct. They are 12V coils so you will be operating them as 6V coils and it will be 1/2 the current but at 100% duty as well so it might take awhile to heat up but at least it will be controlled.

for a single coil
V=12 V
R=3 ohms
I=12/3=4 amps
Duty Cycle= 50%
P = I^2*R * DC = 4*4*3*0.5=48/2=24 watts

for series coils
R=3+3 ohms
I = 12/6=2 amps
DC = 100%
P=I^2*R*DC = 2*2*6*1.0=24 watts total which is 12 watts per coil


So the charger keeps you from running down the battery too much.

The fuse is just in case something evil happens.

If you find it is not heating up fast enough then use a single coil and the fuse to get it to heat faster but then you will be jumping up to 48 watts.

[pdqford]

I would want to check the coils. Did you use an ohm meter to check both to see they are the same resistance?
EDIT: I see you checked the resistance. HUM

Does that mean he checked the primary resistance only? How about the resistance between the primary windings and the secondaries?

(I don't know if these coils can physically short the primary to the secondaries when they heat up? But if they did the primary resistance would still check out okay.)

(Problem with checking out a coil with an ohmeter is it will only tell you if the coil is bad. It won't tell you if the coil is good. An amp clamp on the primary viewed through a GMM or DSO will show the current ramp to determine if the coil primary is saturated. But I understand, you gotta work with what ya got.)

[MisterCinders]

Does that mean he checked the primary resistance only? How about the resistance between the primary windings and the secondaries?

(I don't know if these coils can physically short the primary to the secondaries when they heat up? But if they did the primary resistance would still check out okay.)

(Problem with checking out a coil with an ohmeter is it will only tell you if the coil is bad. It won't tell you if the coil is good. An amp clamp on the primary viewed through a GMM or DSO will show the current ramp to determine if the coil primary is saturated. But I understand, you gotta work with what ya got.)

I checked the resistance at the primary (about 3 ohms) and the secondary (30,000 ohms).

Update, double checked the coil voltage. With the ignition on the battery reads about 12.8 volts and the coils read about 12.6 volts.

Pulling the wiring in the headlight bucket and the kill-switch to see if there's anything loose that might intermittently cut power to the coil relay.

Will also check the HT lead connections at the coils. They seem solid, but a closer inspection might reveal more. v0v

[pdqford]

I checked the resistance at the primary (about 3 ohms) and the secondary (30,000 ohms).

And there should be infinite resistance between the primary and the secondary.

[MisterCinders]

And there should be infinite resistance between the primary and the secondary.

Cool. I'll check that too.

[posplayr]

Cool. I'll check that too.

pdqford is correct in that the test I described only serves to test the primary. But since you blew a fuse that seems to be part of the problem. The other thing to check is if the secondary resistance drops when hot.

A volt meter between ground and the secondary would show voltage is there were any short between primary and secondary (while voltage is applied to primary).

[MisterCinders]

Resistance check on the 1/4 coil shows high 100, 000 but not infinite ohms across ht lead and orange wire connection. 2/3 shows infinite. Does this mean bad coil?

[posplayr]

Resistance check on the 1/4 coil shows high 100, 000 but not infinite ohms across ht lead and orange wire connection. 2/3 shows infinite. Does this mean bad coil?

Yes probably and it probably gets worse with temp.

[MisterCinders]

Yes probably and it probably gets worse with temp.

Thanks. Just e-mailed Dynatek, as I bought them last September. SO I am within the 1-year warranty period.

[Gonzo]

Sounds very similar to what I have going on. The universe might be playing a cruel joke and GSers are the butt of it.