Topic: Resistor plugs and suppression plug wires

[Scootch]

Anyone have experience with using resistor plugs with suppression wires or resistor caps? I have been wondering what results that would give. Would plugs fire? Would everything work just fine? Would it run like crap?

[Don R]

 I've read that adding resistance will make the spark longer duration but weaker, up to the point where it doesn't work. Old caps may have varying resistance readings, newer 5K caps and resistor plugs may work but are you trying to achieve some goal or just wondering?
 
 I have a Gerex CD ignition with resistor wires on a 750, it draws a lot of juice from the charging system but makes a good multi-spark below 3K rpm.

[Scootch]

I am just wondering. Electrically it doesn't make sense to use resistor plugs with suppression wires and/or caps.

[Nurse Julie]

Originally, when the Hondas fours were built, the plug caps were just a metal shroud, with no resistance so resisted spark plugs were used. Honda told dealers to throw the metal shrouds in the bin at PDI as it was like a firework display in the rain with them shorting out , we get a lot of here in UK 🙄, and fit resisted NGK plug caps. But, by what I can remember, there was never any mention from Honda to remive the resisted plugs and fit non resisted.
Through years of ownership, many of us worked out that if you changed the plugs to non resisted when using the resisted plug caps, the bikes ran a lot better. I've been using resisted NGK caps and non resisted D7EA (or D8EA depending on which Honda four it is) since 1979 and all my bikes have run and still run perfectly. On the one occasion I accidently went back to resisted plugs in error, the bike ran like #$%*e.

[Scootch]

I just made new wires for my CB. 7 mm stranded copper wire center conductor. D7EA plugs. Only have one ride under my belt. I was running 8.8 mm graphite conductor suppression wires with 5 kohm caps. I had found a problem with the graphite wire. #3 cylinder had been giving me fits. I finally found that the cap on that #3 wire was not making good contact with the graphite center conductor. After I fixed that the bike was running good. I just decided to experiment with wire center conductors and no resistor caps. We shall see...

[Deltarider]

I just made new wires for my CB. 7 mm stranded copper wire center conductor. D7EA plugs. Only have one ride under my belt. I was running 8.8 mm graphite conductor suppression wires with 5 kohm caps. I had found a problem with the graphite wire. #3 cylinder had been giving me fits. I finally found that the cap on that #3 wire was not making good contact with the graphite center conductor. After I fixed that the bike was running good. I just decided to experiment with wire center conductors and no resistor caps. We shall see...

In short: graphite center conductor wires are definitely a no no.

[Deltarider]

Originally, when the Hondas fours were built, the plug caps were just a metal shroud, with no resistance...

A seller measured 5,8kΩ though... https://www.ebay.co.uk/itm/166025530008
So the question remains: was that metal shroud there to deal with "noise" (interference) or was it there to shield the resin made cap against heat?

...so resisted spark plugs were used.

Sure? Or is this typo and did you mean resisted plugcaps
I am not sure R type plugs were even around back then.

Honda told dealers to throw the metal shrouds in the bin at PDI as it was like a firework display in the rain with them shorting out , we get a lot of here in UK 🙄, and fit resisted NGK plug caps.

Yep, the metal shrouds were causing problems. I've discussed this on the German forum, where some members still fit them for sentimental reasons. So far they gave me conflicting answers about resistance or not in these caps. A seller measures 5,8kΩ... https://www.ebay.co.uk/itm/166025530008

But, by what I can remember, there was never any mention from Honda to remive the resisted plugs and fit non resisted.

Makes sense, because I can't remember anyone used R plugs in those years and - as said - I doubt they were around.

Through years of ownership, many of us worked out that if you changed the plugs to non resisted when using the resisted plug caps, the bikes ran a lot better. I've been using resisted NGK caps and non resisted D7EA (or D8EA depending on which Honda four it is) since 1979 and all my bikes have run and still run perfectly. On the one occasion I accidently went back to resisted plugs in error, the bike ran like #$%*e.

This is consistent with what two Dutch workshops that deal with these bikes on a daily basis, say.
Although some claim a beneficial effect on the burn period by adding extra resistance, this effect has never been demonstrated and after all the research I've done, I tend to consider such a beneficial effect an urban myth. Claimers have had ample time to demonstrate such an effect, if any.
The suppressors, either metal shrouds or resistors are there to avoid radio interference and that's all to it.
From experience I recommend just the simple, pretty reliable NGK resistor plugcaps and abstain from R plugs. All those mecs at dealer workshops that have dealt with thousands of these bikes back then, cannot all have been wrong.

[fizzlebottom]

My bike's service manual does call for both resistor plugs and resistor caps, totaling 10k of resistance. I installed equivalent NGK caps and plugs and have experienced 0 issues. But I also recognize that my bike is a weird unique snowflake in the Honda SOHC/4 realm, so almost nothing crosses over to other models.

[TwoTired]

Essentially, resistance does not matter or effect voltage until current flows.  The spark plugs don’t fire or draw current until there is enough voltage present across the gaps of both spark plugs to form a plasma conductive channel in the spark gaps.  Only then does circuit resistance matter.  During the spark event, the resistance determines the rise time of the current surge.  More resistance reduces the steepness of the slope rise and meters the duration of the event by delaying the charge dump of the coils.  Two things of note happen.  1. Reducing the discharge slope lowers the radiated impulse frequency response on the high tension unshielded wires, reducing RFI energy (Radio Frequency Interference) broadcast from them.  2. The resistance delays the transfer of energy and creates a longer duration spark event since the coils can’t dump their energy as fast as without the resistance.  While lower added resistance can result in a “hotter” spark, it also removes metal from the electrodes in a polarity specific direction (see Electrical Discharge Machining or EDM).  I notice that most 750s came with 5k plug caps, while the 550s came with 10k plug caps.  The coil resistance was very nearly the same for both models.  Also, the 750 used a colder plug than the 550.  The hotter plug of the 550 would normally erode faster without the added resistance of the 10k plug caps, lowering EDM effects of the spark event currents.  Some regulatory agencies required 10k caps for importation solely to reduce RFI effecting radio and tv reception of the day.  But, there are other very good reasons to have the proper resistance in your ignition circuits.

[Deltarider]

The ignition system has no knowledge of volts, ampères or ohms. They don't exist in real life. We humans have invented them, so we can work with a phenomenon called electricity. Even the word electricity itself is debatable when we discuss ignition systems. The sparkplug needs energy (some specify this energy as heat) between its electrodes. Scientists therefore rather talk mJ, Joules or millijoules here. Good luck finding mJ on your DMM . Going into details of details about ohms, microFarads and what have you, may be a great way to profile one as an 'expert', but as long as we can't proof any benificial effect on the ignition process - and let me remind you that no one so far has reported any benefit - it's better to rest the case, till we may know more.
This is a good opportunity to express my frustration over people on the one side claiming all kinds of things, which can never be repeated/proven and folks on the other side who swallow it like candy. The fact that this subject is nowhere to be found outside this forum, strengthens me in my opinion that an eventual effect is trivial at best.
The discussion reminds me of the debate between scholars in the Dark Ages, about questions like how many angels can sit on the tip of a needle. History never revealed who came out as the winner of that debate.

[RAFster122s]

The more I see Delta's drivel the more I want the forum to have a mute user feature.
One second he tosses out the window science's attempts to quantify and name and explain things then he magically starts talking millijoules and similar scientific concepts.
Paradoxical

Engineers are taught low level details of hows and whys and the technicians that maintain and repair don't require that same depth of knowledge...
So, the audience and their level of education and understanding are taken into account in some situations.
Physics teaches electricity using current flow while entry electrical engineering technology programs don't initially introduce it that way. Once the basics are understood and you start down the path of circuit analysis you start learning the current flow method from negative to positive...

So, you keep your understanding Delta and your viewpoints. Personally I will believe HondaMan and TwoTired and many others