Engine dies randomly while riding

[Gorminrider]

Please correct me if I'm wrong-I'm speculating based on the wiring diagrams...as to what is in the "black-box", coils ,sensors..well I'd have to dig around in my archives to sound more knowing but t:
as comparison, my gsx400 with Transistor Controlled Ignition and two coils, grounds each coil independently using the signal from one of the two pickups on the crank. (Advance is controlled mechanically in these)
I guess I could run out and do a setup as in the video...someday... then I'll know
In your diagram, I think I see that the single coil is grounded on every signal from both pickups on the crank...(I suppose advance is electronically controlled)


thanks! If this is the fix, it's pretty useful to know.

I am currently running resistor caps PLUS resistor plugs.

Prior, I was running resistor caps with NKG B8ES plugs when the problem was occurring.

ADD: concurrent with this thread is https://www.thegsresources.com/_for...dalone-diagram-proposal&p=2512270#post2512270. See the diagram from the "ignitor" to coils involves two different colours to the ground/- side of each coil. That is the crux of it, versus your diagrams

 

[posplayr]

Please correct me if I'm wrong-I'm speculating based on the wiring diagrams...as to what is in the "black-box", coils ,sensors..well I'd have to dig around in my archives to sound more knowing but t:
as comparison, my gsx400 with Transistor Controlled Ignition and two coils, grounds each coil independently using the signal from one of the two pickups on the crank. (Advance is controlled mechanically in these)
I guess I could run out and do a setup as in the video...someday... then I'll know
In your diagram, I think I see that the single coil is grounded on every signal from both pickups on the crank...(I suppose advance is electronically controlled)


thanks! If this is the fix, it's pretty useful to know.


ADD: concurrent with this thread is https://www.thegsresources.com/_for...dalone-diagram-proposal&p=2512270#post2512270. See the diagram from the "ignitor" to coils involves two different colours to the ground/- side of each coil. That is the crux of it, versus your diagrams

Based on the manufacturer's schematics, you are correct in that there are two pulse signals from two pickups each of which shorts their respective outputs (white and black) for a short period following a pass of their respective pickups. The rest of the time they (black and white) go open circuit.

So quite simply if in the single coil example if you connect both black and white to the same coil (-), it will fire twice per crank revolution.

If you are doing a 540 degree firing it gets worse for one of the coil cycles(shorter time) and better for the other(more time).

 

[Gorminrider]

Well, I went to look it up and I see that this FAQ mentions intermittent failure due to plugs and leads...http://www.boyerbransden.com/faq.html

Our Micro Digital and Micro Power ignition systems contain a small computer operating at high speed that can be adversely affected by radio frequency interference. Symptoms can range from refusal to start to intermittent engine stalling symptoms. Use of non-suppressed plug caps has been known to cause permanent damage to the ignition unit.

further it mentions 5k ohm

For all our motorcycle ignition systems, copper wire leads with 5000 Ohm suppressed plug cap is our preferred method, although the MK4 systems can be used without any suppression on the H.T. leads if required. When using Suppressed spark plugs, non-supressed caps are recommended. We don't recommend carbon core HT leads because the resistance of the core will vary with the length used and can increase greatly with vibration and age. Although this increasing resistance should not damage an ignition unit, the ignition coil will work at higher voltage and the spark at the plug will become progressively weaker as the core degrades. All Micro Power kits are supplied with copper core HT lead.

but why you also need suppressed plugs ...? You're experience would be interesting to them...

 

[posplayr]

Well, I went to look it up and I see that this FAQ mentions intermittent failure due to plugs and leads...http://www.boyerbransden.com/faq.html


further it mentions 5k ohm

but why you also need suppressed plugs ...? You're experience would be interesting to them...

Ha they have a conducted emission problem with the ignitor!!!

This is the first problem you have to address in these type of system designs. I guess they overlooked a few things.

The double vs single coil may be a red herring, but you would have to look at the specific details. There is a lot of energy in a coil and a lot of it reflects back from the secondary to the primary and that is what the Ignitor's computer sees.

The typical voltage rating on the devices used to short coils in over 500V. That is because of the 10K+ volts on the secondary getting reflected back.

Devices like the Dyna-S are just dumb logic without any computer. This is much less susceptible. A computer runs at 3.3-5V or less and so you need alot fo protection with 500V on one of your grounds.

 

[Gorminrider]

Ha they have a conducted emission problem with the ignitor!!!.......There is a lot of energy in a coil and a lot of it reflects back from the secondary to the primary and that is what the Ignitor's computer sees.

gee,that's a thought...I was kind of wondering why the secondary coil itself would need extra "resistance" in the leads or caps or plug beyond some imagined "heating" ...I was thinking t'was similar to a ballast on the primary but I guess not, eh? Makes more sense.

 

[posplayr]

gee,that's a thought...I was kind of wondering why the secondary coil itself would need extra "resistance" in the leads or caps or plug beyond some imagined "heating" ...I was thinking t'was similar to a ballast on the primary but I guess not, eh? Makes more sense.

I learned all about this in the mid 70s. I had a 1964 Chevelle SS Malibu with a 327 that I have rebuilt and gone through and the thing was still driving like He!!. I drove it cross country that way and while gas was still a lot cheaper, I was in college so every dollar counted. My old boss put the car on his Sun Machine and even showed me arching that was going on between the coil connections and the high tension wire. It was bad plug wires causing the spark to bounce off of high impedance in the wire and come back into the primary. It was not doing anything to the points just not getting adequate spark to the plugs. Ran a whole lot better after changing the wires.

Any way that secondary voltage can come back and couple into the primary. The primary is not just 0-12V it easily goes up to +50V just with stock parts.

 

[Gorminrider]

the primary is not just 0-12V it easily goes up to +50V just with stock part

ah so! ....this has to be a universal issue...from the days when points were used too. I read up on it a bit and where I could find it specifically mentioned ,it seems that (but correct me if I am wrong) the big ol' condensor(capacitor) for points was actually there for it, as much as any spark the 12volts could make as the points open... which is what I've been (lazily) thinking...

 

[posplayr]

ah so! ....this has to be a universal issue...from the days when points were used too. I read up on it a bit and where I could find it specifically mentioned ,it seems that (but correct me if I am wrong) the big ol' condensor(capacitor) for points was actually there for it, as much as any spark the 12volts could make as the points open... which is what I've been (lazily) thinking...

You can think of it this way. There is no spark till the points open. Whatever it is the points opening have to be some small space to break the 12V current of about 3 amps (12V/4ohms=3amps). Now the coil secondary generates a large spark because of L di/dt (i.e. the collapsing magnetic field).
That large spark can reflect back into the primary for a variety of reasons (any kind of impedance miss match of the secondary path down through the wires/plugs/gap).

When this pulse of voltage gets reflected back to the primary, it can easily jump the small just opened point gap. The only way to stop it is to provide a lower resistance path. That is what the capacitor is. It sucks up the voltage/charge and so it doesn't jump the points gap and burn out the points. Of course when the points are closed the condenser (capacitor) is just a DC block and has no impact.


As I said before the actual IGBT parts are rated for like +500V (no typo)

https://www.fairchildsemi.com/application-notes/AN/AN-8208.pdf

Look at Figure two in this document. The voltage range is 50V per division.

https://www.st.com/content/ccc/reso...df/jcr:content/translations/en.CD00003911.pdf

 

[mcquillr]

Update: I test-rode the bike for a few hours today without stalling once! I think we have nailed down the problem!