Topic: Resistor v non-resistor spark plugs and effect on HT voltage

[Scootch]

This is a great video with actual scope pictures and voltage measurements

[TwoTired]

This is a great video with actual scope pictures and voltage measurements

Video quality good, if a bit wordy without need.
Relevance very little to SOHC4
Test procedure faulty
Results not proven , effect speculative and imagined

Unless you have a Gerex unit in your SOHC4,  a CDI ignition fundamentally works different than our simple Kettering style ignition as delivered by Honda.

He didn’t measure voltage at the spark gap.  Probably because that is hard to do. (and, he doesn’t understand how spark is generated.)   He measured voltage on the wire or output of the coil with his shiny new toy scope.  When a resistor is added, the circuit dynamics change, and “where measured” in circuit matters, as voltage varies in different parts of a circuit, especially when resistance is altered in a circuit. He didn’t even bother to do calculations of what it might be at the gap.  He didn’t even notice there were multiple spark events (characteristic of CDI units). And didn’t bother to measure those other peaks being generated from the unit or the overall event duration or the rise times of those peaks whose slopes would be effected by the added resistance.  Further, spark in the chamber is quite different when combustion takes place and pressures rise in the chamber, rather than the observed non-fire conditions.  A fact totally ignored.  But then, he didn’t measure at the spark gap, either.

While he hinted or implied the presented bike would run better with higher spark voltage. He didn’t bother to test or prove his supposition.  And, left the viewer to assume it did.  Engines don’t run on feelings.

On the plus side, he did correctly identify a two wheeled machine as a motorcycle.  Though none that actually ran were presented in this overly long and time wasting video.

[PeWe]

I have tried NGK DR8EIX and Denso IX24 plugs, both Iridium type of plugs  with resistors.

Copper leads with NGK 5 kOhm caps. Plug color looked slightly colder than D8EA.

Both my bikes work fine with resistor caps with non resistor plugs.

I bought Dyna surpressed graphite wires with Dyna-S ignition. 1 wire had intermittent glitch, probably broken inside or bad connected with cap.

Replaced with copper leads, stiffer model that sit better in Dyna coils auto style connection. Too soft wires could glide out, 1:4.

Season is more or less over. I could otherwise give the Irridium plugs another try with correct jetted carbs. Dyna-S ignition and 5kOhm caps.

Dyna 2000 ignition need surpressed wires to not induce disturbances into the ignition. I think those wires have ca 5kOhm resistance.

I wonder if the race guys use Irridium resistor plugs with it?

I used NGK DR8EA in my CB750 back in the 80's. That plug was very common back then.
This with non resistor caps.

There are old threads describing the longer lasting spark when using resistor caps with resistor plugs.

Try it, ride it and check the plug color

[TwoTired]

A note about iridium plugs.

They were developed along with high energy high voltage ignitions to prevent/delay the spark discharge from eroding the electrodes, allowing them to have a far longer life performance expectancy under those conditions, and to meet long distances between tune-ups, like 50K or 100K miles.  This saved dealers from the expense of tune ups under warranty. High energy and standard plugs would erode and create ever increasing spark gaps with use.  However the polarity matters, because most if not all iridium plugs only had iridium on the center electrode.  This is where spark usually leaps from in autos, taking some metal along with it.  All the spark plugs in most if not all autos experience the same polarity applied to them.
In the SOHC4, the current loop for the spark travels through two spark plugs. This makes the spark polarity opposite on half the spark plugs.  So, unless your iridiums have that expensive metal on both the center and strap of the plug, do not expect extended life from iridiums.  And with stock ignition voltages, irdiium is pretty much irrelevant as it provides no different spark than standard.  Iridium doesn't aid spark leap off, it just doesn't melt away as fast as standard. 

I would bet that the parts counterman won't tell you this, though.  Possibly even citing modern automotive performance as "proof", to convince you to "upgrade".

[bryanj]

TT, Suzuki had a job in service to swap plugs 1&4 plus 2&3 to even out electrode wear, this was back in the mid 70's when GS range started

[TwoTired]

TT, Suzuki had a job in service to swap plugs 1&4 plus 2&3 to even out electrode wear, this was back in the mid 70's when GS range started

I didn't know that.  But it makes sense in a wasted spark regime with a coil firing two cylinders.  Assume you re-gap at the same time.

I usually recondition plugs at tune up intervals.  The center electrode gets more rounded on half (don't recall which, though.  I file them flat, as well as the ground strap.  (The spark likes to leap off sharp edges.). Same with the ground strap.  They fire like new for a while.  Actually I rotate plugs I've reconditioned with the set I took out last time.  File them when I feel like it between tune ups.  Clean the center electrode insulator, too.  As long as they don't leak, they get pretty long life.

Cheers,

[Tracksnblades1]

Just want to add, some auto wasted spark ignitions came factory with double platinum plugs.
Eliminating the polarity concerns.

Aviation mechanics have been practicing spark plug polarity rotation for years…

Can one actually grasp the requirements to ignite 1.5 gallons a second.
Makes for dual 44amp arc welders to prevent hydro lock…

[HondaMan]

If it can still be found, I did an oscilloscope test using the Transistor Ignition that included at one point using resistor plugs (I think they were the then-new DR8ES-L from NGK) to see its effects on our own parts. What I remember from it was the slightly longer spark duration: the spark oscillates back-and-forth (positive-to-negative waveforms) a little bit longer with the resistor plugs. This is consistent with normal coil discharge theory, where discharging into less resistance dumps the coil energy faster. The difference in peak voltage in both systems was 1%-2% IIRC, which isn't significant. What IS important is the longer-lasting spark: this helps a lot in city traffic situations at keeping the cylinders burning more completely when hot. Short, hot sparks are not 'the ticket' in the SOHC4 engines we have: it works fine in some others, like 11:1-12:1 compression pentaroof designs, but that's a story for another day.

[Deltarider]

Here we go again...
First that Andy ranks lowest in my list of sources. All show, no quality.
Then this. I didn't know our bikes have a problem with spark duration. Never heard of it outside this forum.
What people sometimes do, is: first make it a problem and then shine when they come along with 'the solution'. This is how advertisements and political speech work.
The ignition system on the CB Fours is adequate and has some reserve. An EI has a fraction more reserve, but that's not the topic here. Folks that continue to believe there is a spark duration issue, will have difficulties explaining how there can be owners who succesfully run their CBs with a simple first generation CDI which has a known ultrashort spark duration. In fact there's practically zero duration.
Then this juggling with Volts. The voltage is just an aspect, it is one way you can look at it and this narrowed look can develop into a tunnel vision. Dyna does good business in bragging about 36.000 Volts. As if there was a problem. They don't tell you, your system already sparks at 7-8kV, also with Dyna coils.
What the electrodes need, is energy, in other words: heat.
And if you prefer to stay focussed on Volts, here's a simple thingie, anyone can make. Look at the pic below. There is a DMM and there's a piece of circuitboard, the size of my thumbnail, hidden inside that oversized protective rubber. I didn't want to pull it out. Instead I have put two identical components in the pic: a condenser similar to the ones on your Honda and a diode. That's all. Attach one lead to the primary, for instance with an alligator clip to the little bolt at the back of your breakerpoints and the black one to GND (frame). The wires on the other side go to your DMM, which you switch into position 600V DC. The diode in the red route rectifies the AC into DC so the voltage can be read and that capacitor across both wires is capable to 'store' the peak voltages long enough to enable a steady reading of them. Depending on RPM and the overall health of your ignition system, you will usually read 200-260V. As long as you have this, there's nothing wrong with the voltage across the electrodes, provided the spark is there and not leaking to the head.
Am I the only one who gets just a little bit tired of these 'how many angels on the tip of a needle' discussions?

[TwoTired]

Ha ha ha ha ha ha ha

[HondaMan]

What people can do is: first make it a problem and then shine when you come along with 'the solution'. This is how advertisements and political speech work.

Bravo!

[Tracksnblades1]

Just wondering out loud.

Does a 89 Suzuki LS400P have the required NGK resistor cap when using the non-resistor B8EA spark plug..

I can’t find an 89 listed in the USA offerings to look up the spark plug cap required.

Perhaps a member across the pond has better access to Suzuki’s 89 LS400p parts..remembering the UK lead the mandatory AM radio noise suppression before all the rest…😁

Wondering  out load again, Did we just watched a New Zealand cd ignition tested with the original engineered resistance cap and a standard spark plug vs  the results of a combination resistor spark plug cap used with a resistor spark plug…🤔