Oe resistor plug caps

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redglbx
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Oe resistor plug caps

#1

Post by redglbx »

Ok, so take all this with a grain of salt because I’m not 100% sure, but here goes. I’ve been struggling for a while now with the fact that I run iridium/resistor plugs along with the 5k oe plug caps. And knowing that all kinds of weird problems crop up when the resistors in the plug caps exceed their specified 5k max tolerance.

So for the past few years my 76 has had an intermittent popping out the exhaust that comes and goes, I am just getting back into riding after a 2yr hiatus due to major back reconstruction, so I’ve only ridden my bike a limited amount and the exhaust popping has been very minimal since replacing the plug caps with new ones that I measured & selected that were all sub 5k pieces.

So this has been bugging me abit as it’s been sensitive to the plug cap resistance and I figured that the addition of the resistor plugs was just to much combined, so the other day we had a conversation here about all this and I think either PID or Whiskerfish said that they eliminate the resistors using a piece of rod. This has had me thinking about all this and all the resistance in my system.

So today I cut & sized some .200in nail piece’s and removed the resistors from my plug caps replacing them with the nail piece’s and the bike seems to idle much better & smoother with no popping/chuffing,,,,,, but only time will tell for sure as I’ve had other times where I was sure I had eliminated this. But it sure seems to idle much better, but as I said take it all, at this time with a grain of salt.

So next I think I’ll get some brass or copper rod and make some better piece’s in my lathe, but it sure seems to run better.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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Whiskerfish
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Re: Oe resistor plug caps

#2

Post by Whiskerfish »

I am pretty tired so take this with a grain of salt also!!

Beyond the RFI reduction I have struggled to find valid references for the purpose of resistors in the caps or plugs. I know some of the reading I have done speaks to spark shaping and spark termination but have not seen any documents that specify the effects of increased or decreased terminal resistance on the spark shaping. I also have read about the "Echo" of spark termination and how higher terminal end resistance can reduce that thereby extending the life of the coil and point/ ignition system. Once upon a time I knew the math to figure Resistor, Inductive, capacitor (RLC) circuits but that is gone, actually the math is pretty basic but the varying time constant of an ignition system make it beyond my ability. Our ignition system is a pulsing DC RLC circuit with a time constant that changes with every change in RPM. That is the part that makes it ridiculously tricky to figure out. Most RLC circuits are Based in Alternating Current with a fixed frequency.

Because I can not come close to calculating the actual requirement, Trial and error has given me the following:
I run Resistor plugs in my 78 with the Green coils and dyna ignition because it has a radio and without them the radio is full of RFI from the ignition. On my 75 with points and stock coils (no radio) I have done away with the resistors in the caps and run regular plugs. It runs good. As a general rule on a stock system I advise one (cap resistor) or the other (resistor plugs) but never both. I do not believe the oem system is strong enough for both. I do get somewhat concerned about running no resistance in the terminal end. Without any terminal resistance the spark will kind of fade away instead of ending abruptly. When it ends abruptly the charging of the coil for the next cycle can begin immediately. When you are dealing with system that has to cycle in microseconds the previous spark cycle hanging on for a few extra ticks can be devastating as rpm increases and the cycle is forced to repeat itself in a shorter and shorter window.
"Agreement is not a requirement for Respect" CDR Michael Smith USN (Ret) 2017
"The book is wrong, this whole Conclusion is Fallacious" River Tam
2008 GL1800 IIIA "TH3DOG"
1975/6/7/8/9 Arthur Fulmer Dressed Road bike
1975 Naked Noisy and Nasty in town bike
and a whole garage full of possibilities!!

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Re: Oe resistor plug caps

#3

Post by pidjones »

I just use cut (with dykes) and shaped (with a small file) #10 wire cut from a piece of Romex house wiring. But, watch those iridium plugs - they are another favorite for counterfeiting (due to higher price, I guess). I wouldn't order them online, but instead buy them at a local NAPA.
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redglbx
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Re: Oe resistor plug caps

#4

Post by redglbx »

thanks guy’s ! Whisker you info is pretty much what the NGK rep/engineer told me years ago, he was adamant that the cap resister was needed to fully charge the coils particularly on our lost spark systems, I think your explanation is spot on.

I’ve been running the NGK iridium plugs for quite a few years now and the bike has run great because they simply do not wear. But over time I have had exhaust popping come & go getting worse in recent years. But as I said I haven’t ridden in the last 2 years but have been chasing the exhaust thing in earnest for the last few months because I was planning to make my GL my main ride because it’s an easy ride & I was going to sell my 14 Fjr.

Anyway not selling the Fjr now but still want to ride my 76 more as it’s just an enjoyable thing,it just runs great past the occasional exhaust farting/poofing, eliminating the resistors seems to have made that better,we’ll see.

PID, I did buy the Iridium plugs from O’Reilly’s a few years ago and well before all the counterfeit stuff really seemed to start. But you never know. If the plug cap mod doesn’t completely eliminate the popping I’m planning to replace the plugs next. We’ll see, only time will tell and replacing the caps with select measured one’s has had an effect so I think I’m in the ball park on this. Again, thanks for your inputs guy’s !
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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Sidecar Bob
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Re: Oe resistor plug caps

#5

Post by Sidecar Bob »

I just replied to this in another thread but as I understand it having some resistance increases the duration of the spark event for a better burn.
And I would expect that most cases of a plug cap's resistance being higher than specified would be caused by corrosion or oxidation causing a poor contact, which is a whole other matter but an ohmmeter can't tell the difference. Cleaning the insides of the cap properly will usually fix the problem.

BTW: I did replace my caps a few years ago but not because of anything internal. One or more of the rubber boots had started to leak and water shorted the spark every time it rained.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
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Another guy with two sidecars..... Hmmmm... must be something to that....
redglbx
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Re: Oe resistor plug caps

#6

Post by redglbx »

So Bob, do you run resistor plugs with the oe 5k caps ? Just curious.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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Sidecar Bob
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Re: Oe resistor plug caps

#7

Post by Sidecar Bob »

Yes. I run the stock DPR8EA-9 plugs plus the 5K ohm caps. If it makes any difference I have GL1500 coils and Dyna S ignition.

I also run DR8EA-9 plugs with resistor caps on my CX (basically a GL500 engine in a CX650E frame) with the same kind of Transistor amplifier Ignition as the GL1100 came with.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
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Whiskerfish
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Re: Oe resistor plug caps

#8

Post by Whiskerfish »

Sidecar Bob wrote: Mon Jun 20, 2022 12:25 pmSNIP
And I would expect that most cases of a plug cap's resistance being higher than specified would be caused by corrosion or oxidation causing a poor contact, which is a whole other matter but an ohmmeter can't tell the difference. Cleaning the insides of the cap properly will usually fix the problem.

SNIP
I have removed and ohm'd out numerous of those cap resistors and found quite a variance with some reading over 10K ohms, just the resistor itself not the cap. I "suspect" the thousands of heat cycles may have something to do with it.
On any bike I try to tune I do a quick basic check from the #1 cap to the # 2 cap and same for 3 and 4. If there are discrepancies then I go further in. Ideal target is about 14.4 K with anything over about 15-16 worth investigating.
"Agreement is not a requirement for Respect" CDR Michael Smith USN (Ret) 2017
"The book is wrong, this whole Conclusion is Fallacious" River Tam
2008 GL1800 IIIA "TH3DOG"
1975/6/7/8/9 Arthur Fulmer Dressed Road bike
1975 Naked Noisy and Nasty in town bike
and a whole garage full of possibilities!!

Psst. oh and by the way CHANGE YOUR BELTS!!!!
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Sidecar Bob
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Re: Oe resistor plug caps

#9

Post by Sidecar Bob »

All the resistors I remember checking were either very close to 5,000 ohms or very much higher but nearly all have been very close.
BTW: NGK used the same resistors in caps that were used on many makes/models.
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
redglbx
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Re: Oe resistor plug caps

#10

Post by redglbx »

Thanks guy’s ! Great info !

I have made it a normal check to check the plug caps if I tune something up and particularly if it’s not running well. I have seen and tested a bunch and in my case anything over 5.5k is when things start going south. And anything approaching 6k definitely has run issues, at least that’s been my experience.

All that said though I do like Whiskers idea of just checking across the wire pairs, so much easier ! I’m anxious to see how my bike runs & goes down the road w/o the resistors, hopefully tomorrow.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
redglbx
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Re: Oe resistor plug caps

#11

Post by redglbx »

As a semi follow-up on all this, I rode my 76 (a real ride) to therapy today which is my first real ride on it in about 2 years other than a couple of quick around the blocks. I did about 60mi today and since you can’t see I’ll tell you that I am just smiling ear to ear, just a wonderful piece ! So smooth and responsive and no pops out the exhaust, 😁😁

Also let me add that my friend fast eddie here has been suggesting for a while now that I put braided stainless steel brake lines on it, I bought some several years ago and just didn’t put them on. So let say I wish he had insisted a long time ago, these are highly recommended! What an improvement in the braking ! I still have the oe wooden brake pads on the front with over 50k on them & the oe master cylinders, what a huge improvement, can’t recommend them enough ! So unless you’re doing an all original show bike just put the Stainless lines on !
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
redglbx
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Re: Oe resistor plug caps

#12

Post by redglbx »

One last thing, I measured one of the iridium plugs (NGK p/n dr8eix) for my 76 gl and it had 4.99k ohms so combined with the plug caps it’s right at 10k ohms combined, which is to much. They shouldn’t be ran together.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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Sidecar Bob
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Re: Oe resistor plug caps

#13

Post by Sidecar Bob »

And yet both of my Hondas work fine with resistor plugs and resistor caps (as do many more - they came that way, after all). I wonder it the popping has something to do with the fact that you are using iridium plugs, or perhaps to do with the gaps they are set at.....
Mr. Honda ('83 GL1100/Dnepr) summer How a motorcycle evolves thread
The Famous Eccles ('84 CX650EI/VeloUral) winter Never Ending Build (CX500forum)
Click: Colour schematics for all GL1000 & GL1100 and GL1200 standard models plus instructions on how to download the full size version
"A guy with two sidecars can't be all bad." - Cookie
Another guy with two sidecars..... Hmmmm... must be something to that....
redglbx
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Re: Oe resistor plug caps

#14

Post by redglbx »

Bob, the iridium plugs may play into it a bit, I don’t know ! There’s also the counterfeit factor on these, which is part of why I’m going to put new one’s in tomorrow, the popping has gotten better with each thing and is pretty much gone. Current gaps are right at .030in. Which should not be any problem with the Dyna ignition & hasn’t been for quite awhile before it cropped up about 3yrs ago. Unfortunately my bike has sat for the last 2 years, so I’ve had to kinda work back up to speed on what’s what and what all I’ve done. The last 2 yrs have been a bit fuzzy, particularly since last July.
Red 1976 oe owner
1976 LTD restored
1980 CBX , in the que, to fix the ignorant heavy handed owner
1981 CBX
1977 CB750 K7
2014 FJR OE owner, sold
1980 GL1100
1984 GL1200 naked
1969 CL350, in the que
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