I keep burning up my cylinder 1/4 coil Update

Patton wrote:

Old Man Rock wrote:

...So, how does over voltage due to charging system or Reg failure, drained battery cause only one coil to be damaged? I mean this is the same Voltage being supplied to both coils...

Now I do understand bad plug wires or resistive plugs on coil/pugs 1/4 drawing excessive current on the SECONDARY side... (think I got that right ) but the charging system/battery theory I'm missing something in what is being depicted....

Am thinking we would agree it's unlikely that coil oozing failure could result from a defective regulator and/or weak battery.

My mental block is in trying to comprehend that coil oozing failure might result from a defective capacitor.

Excessive voltage on the primary winding will arc across the wire insulation and break it down. Eventually, you will get adjacent windings shorting together which will reduce the coil's primary impedance and increase the current flowing into it (and power dissipation) and it will cook.

Can understand where excessive voltage through coil primary winding could short out the windings, perhaps akin to using a 24 volt battery instead of a 12 volt battery.

But still have more questions than answers. For example, when using a 12 volt battery, how does voltage exceed battery voltage in the primary winding between coil primary terminals? Thinking positive battery voltage enters coil primary terminal, goes through the primary winding, then out the other coil primary terminal through the closed points to ground. All the while staying at battery voltage (say 12 volts). This same 12 volts current flow to be interrupted by being ungrounded upon opening of the points.

At the moment the points begin to open, before the gap widens, isn't the same 12 volts attempting to jump across the points (arc), but prevented from doing so by the capacitor which allows time for the points to fully open?

Am perhaps incorrect in thinking voltage across the points doesn't exceed battery voltage. And failing to comprehend how the capacitor functions to increase voltage in the coil primary winding to exceed battery voltage.

Thanks for trying, bountyhunter. But you're so far ahead of me on this that I may never catch up. When it's not covered in the FSM, I sometimes just don't get it. :huh: And it's not due to being mule-headed or stubborn, but just lack of knowledge in the area.

Yikes, the law of inductance police just landed in the front yard! :laugh:

Good Luck!

At the moment the points open, the condenser has zero volts on it, but since the coil's primary current can't stop, the condenser charges up until the voltage reaches between 300 and 500 volts. This voltage is also on the coil's negative primary connection. When the voltage reaches 300 to 500 volts, the voltage on the secondary side is in the tens of thousands (the step up is usually somewhere around 100:1). This is enough to cause a spark on the secondary side. When the plugs arc, the voltage instantly drops lower. The primary side ends up somewhere around 50v while the sparkplug is arcing.

You can think of the condenser as a small time delay. It buys the points enough time to open up far enough so that the 300 primary volts won't arc across the points. The condenser buys time for the points by absorbing a small amount of primary current over a small amount of time. This is because a capacitor takes time to charge.

Without a condenser, the primary current would immediately force a large enough voltage on the points to make the points arc. Since the points were nearly closed, it wouldn't take much voltage to do that. As the points open, the arc on the points would continue until almost all of the coils's energy was expended. The points arcing dissipates primary current instead of inducing the an arc at the plugs.

This diagram shows the voltages after the points open and the condenser is charged, but just before the spark plug arcs. This 350v potential is only for a momentary spike before the plugs arc. While the plugs are arcing, the voltage oscillates around 50v. That is, the voltages fluctuates from like 20 to 80 volts. When the energy is expended, the voltage on the points then returns to 12v.

Thanks for the diagram and additional information, which to me seems consistent with bountyhunter's explanation.

Hadn't before realized that voltage arcing across points contacts far exceeds battery voltage.

Presumably, the 350 volts would also appear with Dyna-S instead of points/condenser.

Good Luck, All !

Yes, all flyback ignition types like on the KZ will have a huge voltage spike at the negative side of the coil. The actual voltage level will mostly depend on the spark plug gap. A larger gap can force that spike to get larger. This can stress out a condenser or electronic ignition.

Electronic ignition tend to have a slightly higher spike since they don't use a condenser. They can usually handle 450 to 600v if they are the older Darlington -transistor type output. IGBT's have since pretty much taken over, but I am not sure what a Dyna S uses. I'm pretty sure the KZ's ignitions use the Darlingtons because they pre-date IGBT's.

That spike is one thing that can eventually lead to the primary side shorting out as the varnish insulation gets old inside the coil.

A good way to visualize it is to think of the electrons going around in the coil like a giant flywheel. You can't stop it instantly when it's rotating, and if you try, it will force the electrons to build up to whatever pressure is necessary to keep them flowing.

(Electrons actually flow opposite of what we typically assign as positive current direction, so in the analogy you can just use fictitious positively charged particles instead of electrons.)

Incidently, if you try to break the ignition circuit at the 12v side and keep the points grounded, you get a giant negative voltage spike on the coil's positive terminal. Either way you will have to deal with an arc.

You can think of a capacitor as a giant tank with two openings and a rubber diaphragm in the middle. You can't fill it instantly, and you can't change it's pressure (voltage) instantly. At rest, the diaphragm is in the center of the tank and there is no pressure. When full, the diaphragm is stretched to one side of the tank, and the diaphragm is under pressure (i.e. the capacitor is charged with particles and has a voltage on it).

After about 40 years of fixing electronic things, I take the philosophical approach: just replace everything that could be a problem and that fixes it.

A coil which is burning up only has two external wires going into it from the system: the +12V power wire into the positive side of the primary, and the points wire on the negative side of the primary. The secondary and HV wires are built into the coil, so changing the coil replaces those making that an unlikely source of failure. That leaves the +12V line or the points line as very likely causes for killing the coil.

I would shotgun the points and condenser (put in new ones) check the +12V line to make sure the voltage isn't too high, and the coil should stop failing.

Here I was all ready to get into transformer theory of operations and Loud & Bounty beat me to it.... LOL!

Think of it this way guys... to generate a electromagnetic field, you basically need alternating current to accomplish. In a DC voltage system the only way to accomplish would be rapid charge/discharge of the pint/capacitor combination.

Ohms Law depicts voltage and current are directly proportional across a fixed resistance.

Same time, resistance & current are in-directionally proportional. Meaning... If resistance goes down my current goes up and vice-versa.

Example, we measure the coil resistance @ 3 ohms (GREEN Dyna Coils) so easy math is 12Vdc/ 3 ohms = 4amps of current in the ON (conduction state) of operations.
But possible due to shorted capacitor, over time the coil becomes weaker and this coil resistance fluctuates to 2 ohms.... Do the math, now you have 6amps of current flowing through the primary henceforth ooze!

Same with the secondary side of the transformer, if shorted on the secondary, this draws excessive current on the primary as well....

All in all, unless this was a fluke where two bad 1/4 coils had been in this bike there's only a couple of true reasons this same coil could be damaged to the point of ooze....

1) shorted capacitor:
A capacitor checker (capacitance measurement) would tell you if it was partially or fully shorted.... For the cost, just replace not worth the hassle...

You could remove one leg of the cap (touch the two legs together to discharge the stored energy) then OHM out and compare the measurement with the 2/3 cap... Not an accurate test but if the resistance values are extreme, there's your answer.

2) How much of a difference is there in the point contacts in pitting and such.... Point 1/4 will most likely be more carbonized & pitted...

3) How much of a difference is there in spark plug insulator coloring comparing 1/4 to 2/3 sparkies... Assumption would be running more richer... not as hot spark. Again, just something to think about due to the fact that this coil damage was over a period of time where the cap is partially shorted versus dead short.... Either case, should have a different coloration on the insulators...

4) On the secondary side... cracks or such in the spark plug conductors... Shorting to engine case... Unlikely but possible.... Again, sparky insulators would be different...

5) Might as well throw this into the mix... Fluke where tow bad coils to start with and this discussion was for not... :huh: :dry: :laugh:

Ok, I'll shut up again.... :laugh:

OMR

FYI, if your condenser is bad you won't see it with a simple meter. The 'shorting" would be occurring under load as the voltage builds up, so you would need a transformer tester that can crank the voltage way up and read leakage current. Same for breakdown in the insulation of the coil windings, you would have to hit it with pretty good voltage to get them to arc.

That's why I would just shotgun the points + condenser, and order a new coil from Z1 Enterprises (they have them very cheap). If you buy a used one, you never know what you are getting. If it came off a 30 year old bike, it's a 30 year old coil....:blink:

if your condenser is bad you won't see it with a simple meter.

... you are correct but my meaning behind this was if dead short... Cap checker truly would be the method. Another reason why I liked the Automotive DVM from Harbor freight Tools... Includes capacitance measurements.

I would just shotgun the points + condenser

So true.... Me, convert over to EI for coils and ihnition plates with new plug conductors as well... Won;t have to worry about it again! :laugh:

Hmmmm,
when I use the term "shotgun", it refers to troubleshooting a problem by replacing or repairing all of the possible causes of the problem, but not in any particular order. One does this because it's faster and easier than actually identifying the exact cause of the problem.

At my work, we often say "shotgun the problem" to mean just replace a bunch of parts until the problem goes away. It's actually more cost effective since time is money, and parts are cheap.

It's called "shotgun" because when you're done, the machine will have a random "shot" pattern of new parts in it. It's also a good term since you are trouble"shooting" the problem. You can take slow, tedious shots with a sniper rifle to hit the exact cause, but often, a shotgun just gets the job done faster.

I think Bounty is saying to just replace the points and condenser with new ones.

loudhvx wrote:

Hmmmm,

I think Bounty is saying to just replace the points and condenser with new ones.

And also put in a new OEM coil, not a used OEM coil and not a "sorta like it" coil designed for a different ignition.

And yes, shotgun means replace everything that could be going bad. A shotgun shoots a wide blast pattern that kills everything in an area as opposed to a single shot that hits what you are aiming at.

Update: Changed the points, condensers, coil, regulator and battery which was just about dry. Checked voltage and everything is correct. Almost everything from Z1 enterprise. All of which were old anyway. I should have just changed them in the begining. Put about 700 miles on it since the parts change. 3645 miles since I bought it. A couple of pics after this weekends ride of over 400 miles.I took the sissy bar off....Russ