What amazes me is ignition systems like the 1998 ZX2 with one "plug pack' for each of the 2 pairs of spark plugs, the high voltage winding wasn't grounded and one end fed each spark plug.

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So one spark plug of each pair was fed the wrong polarity and the engine had still had oodles of power. Clearly if you use enough voltage the wrong polarity doesn't matter.

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A friend raced dune buggies, VW bugs with chopped body, souped up engine, non stock exhaust. They also modified the carbs so idle was a lot leaner because the engines ran so hot and would over heat with VW's wonderful air cooling system just sitting there with the engine running. Even with an external oil cooler, sitting there wasn't good because the external oil cooler didn't have an auxiliary fan.

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There are valid arguments for adding a fan and for relying on the air stream when moving. The fan would restrict airflow at high speed when you need all the cooling you can get. [The VW had a dinky oil pump too]

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So back to lean, it requires a higher voltage to ignite a lean mix compared to a rich mix. Even at red line, the rich mix ignited easier. And that's with point bounce.

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They also didn't use boosted ignition systems, I offered to build a CD system or even a simple transistor switch for my friend and he looked at me like I'd taken a leak in the Baptismal Font.

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I never got it, you change everything but the !@#$$ poor stock ignition system?

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[The bored the engine block to accept larger cylinders, typically doubled the horsepower.]

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I used a circuit very similar to the one shown in this PDF on my Honda CB350 and later on? the CB360 (It was easy to move from one bike to another.)

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https://people.eecs.berkeley.edu/~wkahan/TransIgn.pdf

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Although this poor sod was doomed because he improved the ignition system with a Lucas coil.

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Lucas, Lucas oh lord of darkness.....er excuse me I was having flashbacks to the time I was conned into helping a friend rebuilt a Triumph. [May he roost in a certain hot place for all eternity.]

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My stock CB350 would do 97 MPH with a 140 pound driver [me] laying prone with the stock ignition, it would do over 110 (pegged the speedo) with the transistor ignition. The points bounced too bad long before you reached red line with the stock ignition system for optimal performance.

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The transistorized system closed on the first contact and ignored contact bounce.

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I think I referred to a normal ignition system as supplying the center conductor of a spark plug as supplying positive, oh how I needed to stop and think. The center pin is negative just like the cathode of a vacuum tube.

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The ZX2, and ignition systems that used similar high voltage transformers, treat one spark plug as a normal cathode, but treat the other spark plug center pin as a plate. With enough voltage clearly the wrong polarity doesn't matter.

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I'm not sure how the ECU monitors the ignition system but it will throw an error if a plug fouls. One plug was fouled with oil and the ECU in a ZX2 tripped the check engine light and a code reader returned P030x with X being the problem cylinder. We removed that plug and the plug had burned oil. The owner used one of "spark plug non-fouler extenders" and drove the car another 5 years.

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For a while there were about a dozen of ZX2 owners who'd meet once a month to discuss the car. The biggest problem was the !@#$ trunk leaked. That was a nightmare to fix. Water came in via the tail lights, water 'gutters' on the top and both sides. Permatex makes a flowable silicon designed to seal windshields, it was perfect for flowing into all the rain gutter leaks, a silicon sealant dam above the tail light assembly stopped that.

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On Sunday 23 March 2025 08:58:28 am wn4isx via groups.io wrote:

Too bad this isn't 1960 and the Ed Sullivan show was on Sunday nights because the presenter is a much better comedian then engineer. His escapades would go over quite well with dancing bears and guys who spin plates on poles.

I remember spinning plates, not any bear. Could never see the point of them. 1960 was quite the year, but I'd rather not go back there...

However, he'd be tossed out of, and banned, from any university electronics laboratory for his foolishness.

Suggesting using a resistor divider to reduce direct AC mains to feed a microcontroller is downright stupid verging on criminal.

Lots of stupid stuff out there on the 'net. YT doesn't seem to care.

The way you measure ultra high DC voltages is with a electrostatic voltmeter.

In my real early days of messing with TVs the accepted practice was to arc the HV to the chassis, and see if you got a decent spark. Later on this was frowned upon. Somewhere back there I bought a Polaris branded HV probe, a big long thing with a pointy bit on one end, a wire with a clip on the other to ground it, and a meter. You also had a couple of terminals on either side of the meter which you could use to measure the cathode current of your horizontal output tube. I haven't used it a lot, but I've used it some. Still works well, even though the plastic packaging that wrapped around the box has yellowed and started to self-destruct.

(...)

I've seen this in Honda CB350s, 1968 and 1969 stock VW bugs. The ignition coils in the Honda twins was located where they were heated by the engine, I never had a hard failure but I could tell when it was time to replace one when the power dropped way off and the engine sounded funny, both ignition coils never failed at the same time so the power was really imbalanced between the cylinders. I limped home from Mason Ohio [near Kings Island] to Lexington one night sweating "Will I make it home...."

VW coils just failed for the fun of it. West German manufacture wasn't quite as perfect as they'd have liked for you to believe.

We had a VW bug of around that vintage. It had a blown head gasket, another blown gasket at the base of a different cylinder, and the battery had a shorted cell and wouldn't start it, so we had to push start the thing. Good thing we were up on a hill... We stopped driving that thing when it wouldn't pass inspection any more because it was basically rusting out. My brother was a bit of a VW nut and owned several of them including that little bitty pickup truck, but these days he's driving a Chevy. I guess he's disappointed in "german engineering" or something?

(...)

VW transporter van with Porsche engine

My brother worked at a dealership at one point, and the parts for those two brands are exactly the same. With different prices.

I did have the ignition coil fail on a Plymath Omni, about a month before the engine decided to emulate a grenade. [Way too exciting at 80MPH on the Mountain Parkway at 3:00AM. You've never lived until you have parts of the engine come through the hood right before your windshield is covered in oil and coolant. Loads of unfun.]

You have had more excitement than I have, for the most part. Though I did have a couple of episodes of a wheel departing the vehicle...

(...)

--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, ?a critter that can
be killed but can't be tamed. ?--Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin

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1 - I agree that suggesting connecting mains through a resistive divider to an MCU input is nearly criminal. But I also remember, as a young lad, connecting the line voltage through a diode bridge to a dropping resistor to power some piece of gear I had created. The smoke escaped and I learned something without losing eyes, fingers, or life.

2 - The Paschen curve is representative for smooth (non-sharp) surfaces separated by 0.100in. Spark plug electrodes are sharp-edged, which reduces the breakdown voltage by up to 10x; are spaced 0.025in to 0.030in (reducing the breakdown voltage by another factor of 3x to 4x; and the temperature of the most-negative electrode (since that is where the electrons first get "launched" into the arc) in a spark plug is quite high, further reducing the initiating voltage by another 2x or so. Back to the Paschen curve - it can be extrapolated above 1ktorr because it becomes basically linear on log-log plots; 70kV at 720torr can be extrapolated to (pretty closely) 700kV at 7200torr - but with the sharp edges, the spacing of the electrodes, and high temperature of the center electrode, we can estimate spark plug breakdown voltage as 700kV/(10*3*2) = 11.7kV - reasonably close to my experience: 25kV for a typical auto engine.

Typical ignition voltages (back when I was actively working on them in the late '70s/early '80s) ranged from 25kV to 35kV. The higher voltages were for older plugs with rounded center- or side-electrodes, or for high-performance engines with very high compression ratios.

Fouled plugs can show "good" breakdown and adequate current draw, but with no spark in the gap - all the energy went down the fouled surfaces. The only way we were able to discern good vs. bad plugs without removing them from the engine was to monitor the spark voltage and current waveforms simultaneously.

Donald.

Too bad this isn't 1960 and the Ed Sullivan show was on Sunday nights because the presenter is a much better comedian then engineer. His escapades would go over quite well with dancing bears and guys who spin plates on poles.

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However, he'd be tossed out of, and banned, from any university electronics laboratory for his foolishness.

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Suggesting using a resistor divider to reduce direct AC mains to feed a microcontroller is downright stupid verging on criminal.

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The way you measure ultra high DC voltages is with a electrostatic voltmeter.

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https://en.wikipedia.org/wiki/Electrostatic_voltmeter

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I bought a ESH model 600085 at a surplus sale for $5 that will measure 5, 10, 15, or, 20kV. Other then testing it in a real electronics lab, I've only used it once to measure the high voltage for an night scope (starlight scope) tube power supply.

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However for measuring the ignition voltage for anything other then a model airplane engine, which uses a 1.5V glow plug, one needs something like either the?gizmo made from plastic with a screw adjustable gap to measure the ignition/spark voltage, however this measures the voltage under "no load."

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Or the Leslie unit I mentioned earlier which actually shows you how strong the arc is with the engine running.

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When the cylinder rises during the power stroke, the 'air' pressure increases, if you have an engine with 10:1 compression, then your pressure when the spark occurs would be 10 X 14PSI, 140PSI.

140PSI = ~ 7240 torr.

see the graphic at

http://www.highvoltageconnection.com/images/paschen-curve_clip_image002.jpg

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The chart maxes out at 720 torr and shows the voltage required to be in excess of 70,000V. [I have doubts about this graph but don't feel like working out the math this morning.]

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Wiki goes into Paschen's law in quite a bit of detail.

https://en.wikipedia.org/wiki/Paschen%27s_law

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All of this is interesting from a theoretical angle, but the practical aspect is simple:

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"Just because your ignition system produces a spark/arc in a spark plug outside the engine does not mean it will produce a spark in the engine under compression."

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I've seen this in Honda CB350s, 1968 and 1969 stock VW bugs. The ignition coils in the Honda twins was located where they were heated by the engine, I never had a hard failure but I could tell when it was time to replace one when the power dropped way off and the engine sounded funny, both ignition coils never failed at the same time so the power was really imbalanced between the cylinders. I limped home from Mason Ohio [near Kings Island] to Lexington one night sweating "Will I make it home...."

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VW coils just failed for the fun of it. West German manufacture wasn't quite as perfect as they'd have liked for you to believe.

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I learned more about ignition systems then I wanted with those vehicles. I've never had an ignition coil/system fail in

Chevy Nova [My wife's when she was my girl friend. Car died when someone t-boned it in a parking lot. Bummer]

Subaru [two cars, 1980 station wagon, 1984 compact]

VW transporter van with Porsche engine

[I have no idea why a very similar engine never experienced a fuel pump failure or ignition coil failure.]

Toyota [3 cars]

Ford [1 car we put over 200K miles on.]

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I did have the ignition coil fail on a Plymath Omni, about a month before the engine decided to emulate a grenade. [Way too exciting at 80MPH on the Mountain Parkway at 3:00AM. You've never lived until you have parts of the engine come through the hood right before your windshield is covered in oil and coolant. Loads of unfun.]

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[I always carried a spare fuel filter, fuel pump and ignition coil. <and fan/generator/ belt> for the VWs. I've changed the fuel pump and ignition coil by feel in pitch black dark out in the boonies more times than I care to remember. Yea for a person who collects flashlights it was silly not to have one, but the batteries were always dead when I needed the light. I finally got smart and made a 12V trouble light with 20 feet of wire, a fuse and power port to the battery and never had a fuel pump or ignition coil go bad again.]

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A dying ignition coil can produce what appears to be a very strong arc in a spark plug outside the engine and not work or sort of work in the engine.

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Sort of work to mean, rough idle, stalls when you give it gas.

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Modern automotive/light truck ignition coils are extremely reliable.

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Briggs and Stratton lawn mower ignition coils not so much.....

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Real mechanics with real garages with real test equipment designed for cars often have specialized oscilloscopes that will display the ignition voltage. It's worthwhile getting a glimpse if you have a friendly mechanic.

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I would never consider trying to build an adaptor to allow me to see the ignition voltage waveform on my DSO. One could probably salvage the ultra high resistance resistors from cold war civil defense ion chambers and add plenty of diode protection clamps but I'll let others fry their DSO when the Leslie ~$20 device works very well.

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BTW I have no business relationship with Leslie, I'm just a very satisfied customer.

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For the really brave...[or foolish]

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I have no idea if the device will work or fry your scope.

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Ya pays your money and takes your chances. [not me.]

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Oh changing the two drive belts was amazingly easy, took two hours, mainly because I removed the pulies and lubricated them [one bearing will need replacing sooner then later, it's on order] and cleaned the space under the deck, used a wire brush to remove some rust and painted it with a high quality epoxy paint, and I blew dead grass bits out of 'everywhere.' I also added a kill switch to the seat, get out and the engine shuts down. The twins are a bit careless. I do not want anyone to lose a foot. [Yea I'm paranoid.]

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1 - the Freon also provided insulation for the voltage divider resistors. When the Freon eventually leaked away, you could see the corona on the internal connections.

2 - the polarity of the spark (at compression pressures) makes a huge difference. Driving the center electrode (which is much hotter than the side electrode) negative saved a couple thousand volts. The wasted spark doesn't need very much voltage - something on the order of a few hundred volts - or take very much from the working spark because it's firing into exhaust gases, which are already hot and ionised, and at a quite low pressure (slightly above atmospheric).

3 - The Leslie spark indicator (or something like it) is old, but effective, technology. My dad's timing light was basically a housing with a lens holding a neon lamp that went in series with plug #1.

Donald.

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Back when I was doing automotive ignition system system development, we used a Tektronix HV probe, quite similar to It required a Freon charge inside the forward plastic housing (I believe to cool the dropping resistors) and was finicky to use.

Donald.

We were discussing batteries a few weeks ago and I mentioned I used high value capacitors, AKA super capacitors, to replace the 3V lithium disk cell.

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I received an email asking for details.

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All of the receivers have a 5V rail, I used a 4 1N914 or 1n4148 small signal silicon diodes between the 5V rail and positive of the super capacitor to drop the voltage. The nominal voltage drop of a silicon diode is 0.7V, however under extremely low current this can drop to as low as 0.5V. It will vary from diode to diode even in the same family.

I also included a 100 ohm resistor just in case, I like to always have current limiting.

The V+ of the super capacitor was connected directly to the V+ memory backup.

In my first installation I did things a bit different. I used a 1K resistor from V+ 5V to a string of 1n4148 diodes to give a "regulated" V+ between 2.5V to 2.9V. Memory keep alive in the R-2000 is 2V.

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I adopted the first version I described after some thought and experimentation with a R-2000 with a defective tuner optical pulse decoder on the main PCB that defied repair.

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You can tune the radio, it's just a royal PITA that can take an hour to tune to the desired frequency. I programmed in useful frequencies in all 10 channels and treat the radio as a fix tuned radio. I have WWV on 2.5/5/10/15, CHU on 7.850, and, US Global HF Network 4.7240, 8992.0 11.1750, 15.0160 and 11.2320 [interoperations with Canadian forces].

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My super capacitors came from the factory keep alive PCB in Kenwood commercial radios, these PCBs were removed and trash after the PCB with all the programmed channels was installed.

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I've modified 10 Kenwood R-2000 general coverage receivers and 2 iCom IC-28A 2M amateur transceivers. I'll be modifying 3 more IC-28A in the near future.

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My super capacitors are 30 years old and are 4.?F, One R-2000 was not powered up for at least 4 years, probably 5 and half, all the memory channels were still there.

Modern higher value super capacitors might have higher internal leakage. I've ordered some 100F 3V supercaps to experiment with.

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Supercapacitors have odd chemistry and I suspect they will last longer if they are kept biased at their operating voltage. I was given about 30 of the Kenwood keep alive boards, pulled the supercapacitors and they are on a 3V rail powered by my primary 12V ham radio power rail.

They've probably been without power for maybe a week since I wired them to the 3V rail.

My experience with the R-2000 that was powered off for at least 4 years suggests the chemistry is more robust then I initially suspected, but, the supercapacitors are in a dedicated plastic box and I see no reason to remove them from the power. [I'm too lazy to change some things without a good reason.]

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All of this came about because I couldn't find a replacement battery in Lexington and didn't want to wait for mail order, well that plus the memory back up cell in the R-2000 is soldered in, which means you have to remove all the very flimsy (cheap) connectors.

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I was initially going to mount a 2 AA battery holder on the rear of the R-2000 when I was given the Kenwood "keep alive" PCBs and decided to give a crazy idea a try.

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YMMV

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