Topic: Question about plugs and caps

[Silver Wolf]

Good afternoon! I recently bought 2 CB650C project bikes. First engine came with DR8EA plugs installed, while the second bike's engine had the correct D8EA plugs installed.

When using stock plugs, the caps should have 5K resistors in them as far as I can tell.

With the DR8EA which has 5K resistor in the plug, does that mean I use caps with no resistor?

Thanks

Wolf

[Deltarider]

Various models (read:markets) had various resistances. Had to do with legislation. The general advice for all bikes is to have 5kOhm per lead.

[Sw1ssdude]

the resistors were supposed to keep the ignition from emitting high frequency radio waves, which could interfere with police radio or those old timey TV sets with an acoustic remote which simultaneously changed channels and made your dog flinch. (at least this is how i learned it. Capacitors would be way better at dampening HF ripples, but they tend to inhibit sparks altogether, as they do on the points side of the ignition system. not ideal for SPARKplugs..)

it has also to do with the duration and shape of the spark. you can easily measure the resistance between the sparkplug side and the lead side of the cap, it should read 5k ohms (give or take). a couple of ohms (close to zero) means that you have non-resistor caps, and no continuity means that your resistor is broken. In this case the cap might still work, but by chance, not by design. meaning that every spark has to jump two gaps, one at the spark plug and one inside the cap.

most important with the waste spark design like on the sohc/4, you have to check both spark plugs of the same coil simultaneously, or at least have the other spark plug connected to ground, as the built up high tension in the coil runs through one plug into the motor, and from the motor through the other plug back into the coil.

its good advice to have 5kohm resistance in your system, one way or another, as designed (there are caps with higher or lower resistance, too).

i find it harder to find non-resistor plugs to go with my original resistor caps in shops in my area (switzerland). i might switch someday, but new resistor plugs with new non-resistor caps aren't cheap either...

[Deltarider]

[...]
it has also to do with the duration and shape of the spark. [...]

In all of my research over the last 10 or so years, I have seen no mentioning/indication - let alone proof - of a beneficial effect by adding extra resistance. Only here in this forum. I consider it an urban myth. 

[Sw1ssdude]

it might be true that it is an urban myth.

as i read (over the years, in various forums), the resistor is supposed to spread out the current flow over some more time, allowing for a longer duration of the spark, instead of a very sharp and instantaneous peak current, you supposedly have a longer 'plateau' current. sounds reasonable to me, but dont know if this holds up. The NGK lexicon also describes the purpose of the resistor as a filter for interfering HF frequencies. it also states that leaving out intended resistors might result in rough idling:

Since resistor type plugs actually “resist” some of the spark energy, non-resistor type plugs actually deliver a more powerful spark. It is for this reason that most racing plugs are non-resistor types. However, in most automotive applications, a resistor plug is required for proper vehicle operation. Use of non-resistor plugs in vehicles that call for a resistor type can result in rough idling, high-rpm misfire, and abnormal combustion.
https://www.ngk.com/what-is-a-resistor-spark-plug

just make sure you have resistors (plug OR cap) in your original system as designed by mister Honda, and you should be fine. Unless you have a really tricked out ignition, in this case you're on your own...

[Deltarider]

it might be true that it is an urban myth.

as i read (over the years, in various forums),

Clearly you have been more succesful than me in finding other sources. I have knowledge of only one forum - for light pleasure aircraft - but that particular post was withdrawn later. The poster was identified by a member in this forum as the same person that has spread the theory of a longer spark duration in this here forum. It goes without saying I am interested to read what you have read.

the resistor is supposed to spread out the current flow over some more time, allowing for a longer duration of the spark, instead of a very sharp and instantaneous peak current, you supposedly have a longer 'plateau' current. sounds reasonable to me, but dont know if this holds up. [...]

What you describe here, fits the difference monitored in reality (!) between a CDI and a conventional or a non CDI EI. Some bikes benefit from CDI, some don't and there are bikes where it makes no difference.
As I see it, the combustion process in our oldfashioned engines is so utterly, utterly primitive that it will be quite a challenge to monitor a significant difference in performance when resistance in the secundary circuit is altered. As always I'm open to learn something new, but for now I stick with the advice NGK and Honda mechanics have given me. I've concluded that Canada must have had other legislation than elsewhere and I don't rule out batches that had that same noise suppression have been shipped to US and EU.
My gut feeling is that differences in gap at the sparkplug's electrodes will give much, much more effect.
If you want to be sure you have enough spark duration, stick to the standard, by Honda prescribed gap, if you look for a somewhat higher voltage in the initial peak voltage, you may experiment with a slightly wider gap.
Here is a question for the experts. In particular CB500/550s are known to easily foul their sparkplugs at idle. What - in theory - would make these CB Fours idle better: an electrode gap of 0,6mm or 0,7mm? Please motivate your answer.

[Oddjob]

Back to the original question.

It would appear the correct plugs for a CB650Z are resistor plugs and the caps are also resistor caps, XD05F caps to be exact. This could be because unlike it's predecessors the CB500/550 it doesn't use points and condensers but a pulse generator system. The coils are also much different in having removable plug leads. Electronic coils tend to need higher resistance in the system so that may account for the 5K in the plug and in the cap, so 10K in total.

[willbird]

it might be true that it is an urban myth.

as i read (over the years, in various forums),

Clearly you have been more succesful than me in finding other sources. I have knowledge of only one forum - for light pleasure aircraft - but that particular post was withdrawn later. The poster was identified by a member in this forum as the same person that has spread the theory of a longer spark duration in this here forum. It goes without saying I am interested to read what you have read.

the resistor is supposed to spread out the current flow over some more time, allowing for a longer duration of the spark, instead of a very sharp and instantaneous peak current, you supposedly have a longer 'plateau' current. sounds reasonable to me, but dont know if this holds up. [...]

What you describe here, fits the difference monitored in reality (!) between a CDI and a conventional or a non CDI EI. Some bikes benefit from CDI, some don't and there are bikes where it makes no difference.
As I see it, the combustion process in our oldfashioned engines is so utterly, utterly primitive that it will be quite a challenge to monitor a significant difference in performance when resistance in the secundary circuit is altered. As always I'm open to learn something new, but for now I stick with the advice NGK and Honda mechanics have given me. I've concluded that Canada must have had other legislation than elsewhere and I don't rule out batches that had that same noise suppression have been shipped to US and EU.
My gut feeling is that differences in gap of the sparkplug's electrode will give much, much more effect.
If you want to be sure you have enough spark duration, stick to the standard, by Honda prescribed gap, if you look for a somewhat higher voltage in the initial peak voltage, you may experiment with a slightly wider gap.
Here is a question for the experts. In particular CB500/550s are known to easily foul their sparkplugs at idle. What - in theory - would make these CB Fours idle better: an electrode gap of 0,6mm or 0,7mm? Please motivate your answer.

Well we are not riding a model A ford that has 4:1 compression LOL so perhaps not as crude as you describe LOL. I have seen some "Hot Rod" type articles describing a "new" innovation introduced for V8 engines some of which had 2 valves and pushrods....and the "new idea" was present in early 1970's Japanese motorcyle engines :-).

I think a drop in system that had a crank trigger as well as providing an electronic advance curve would give the best bang for the buck for our bikes. Some DO exist but they are not hugely popular and some are not built on the same continent I choose to live on. Also in the mix is availability of electrons to run the coils that would be the simplest ones to use.

I do know that one person I follow on YouTube fried a couple aftermarket ECU, maybe Holley stuff by using copper core spark plug wires rather than the "resister" type. Not applicable to our bikes as made OEM but could crop up as an issue with a drop in system.

There are two things we face with these older bikes, advancers and springs, and points-condensers. The HondaMan system that I run eliminates the need for condensers and makes the points last a long time but they are still a finite resource currently.

Bill

[willbird]

Back to the original question.

It would appear the correct plugs for a CB650Z are resistor plugs and the caps are also resistor caps, XD05F caps to be exact. This could be because unlike it's predecessors the CB500/550 it doesn't use points and condensers but a pulse generator system. The coils are also much different in having removable plug leads. Electronic coils tend to need higher resistance in the system so that may account for the 5K in the plug and in the cap, so 10K in total.

I bought a "microsquirt" ECU and I am planning on setting it up on my K3 getaway bike. Once I started to dig into ignition systems in general I had some conceptions that I had developed over the years that turned out to be incorrect. One was that dwell in milliseconds of our older systems was exponentially longer than in say a Chevrolet LS v8 as one example, or a VW that provides a really simple coil that may be easy to work with as a starting point. Turns out that the actual dwell time in milliseconds is maybe a bit different but not as much  so as you might think.

Here is one example of a coil that I picked up to play with, where to mount it, etc was not a primary concern just to get an EFI system at least running. 4 coils in one package, avail at an auto parts store in a pinch, etc. Could be run waste spark or 4 individual sparks. It has built in "igniters" so firing it is just logic level...no real current needed.

https://m.media-amazon.com/images/I/713oq5BQ1VL.__AC_SX300_SY300_QL70_FMwebp_.jpg

Could be a veer off topic but just explaining the reason that I started looking at what really happens with our existing systems as built OEM. The folks who understood ignitions already knew all of this stuff ;-). The top fuel guys are locked into what kind of ignition they use by rules...they think that they COULD get some benefits from an improvement, but the sanctioning body perhaps does not want to have an ignition tech war erupt so they are locked into a dual magneto system that may not have changed since the 1970's.

EDIT: CDI is a whole nother thing, the LS and VW stuff is not CDI. The LS stuff has a "feature" where if you dwell the coil too long it just fires itself, would not hurt anything on our bikes but it will break things if you are running 50psi of boost or a lot of Nitrous :-).

Bill

[M 750K6]

.... The NGK lexicon also describes the purpose of the resistor as a filter for interfering HF frequencies. it also states that leaving out intended resistors might result in rough idling:

.... However, in most automotive applications, a resistor plug is required for proper vehicle operation. Use of non-resistor plugs in vehicles that call for a resistor type can result in rough idling, high-rpm misfire, and abnormal combustion.
https://www.ngk.com/what-is-a-resistor-spark-plug
...

This may be for where EI is used, rather than points. On my '75 Norton Commando I use a Boyer Bransdon EI (with its own advance curve), in place of the points plate and advance mechanism. That requires 5k Ohm resistance in the HT cap, or plugs. It is to prevent the electrical 'noise' affecting the EI transistors. TriSpark is the same.

[Tracksnblades1]

it might be true that it is an urban myth.

as i read (over the years, in various forums),

Clearly you have been more succesful than me in finding other sources. I have knowledge of only one forum - for light pleasure aircraft - but that particular post was withdrawn later. The poster was identified by a member in this forum as the same person that has spread the theory of a longer spark duration in this here forum. It goes without saying I am interested to read what you have read.

the resistor is supposed to spread out the current flow over some more time, allowing for a longer duration of the spark, instead of a very sharp and instantaneous peak current, you supposedly have a longer 'plateau' current. sounds reasonable to me, but dont know if this holds up. [...]

What you describe here, fits the difference monitored in reality (!) between a CDI and a conventional or a non CDI EI. Some bikes benefit from CDI, some don't and there are bikes where it makes no difference.
As I see it, the combustion process in our oldfashioned engines is so utterly, utterly primitive that it will be quite a challenge to monitor a significant difference in performance when resistance in the secundary circuit is altered. As always I'm open to learn something new, but for now I stick with the advice NGK and Honda mechanics have given me. I've concluded that Canada must have had other legislation than elsewhere and I don't rule out batches that had that same noise suppression have been shipped to US and EU.
My gut feeling is that differences in gap of the sparkplug's electrode will give much, much more effect.
If you want to be sure you have enough spark duration, stick to the standard, by Honda prescribed gap, if you look for a somewhat higher voltage in the initial peak voltage, you may experiment with a slightly wider gap.
Here is a question for the experts. In particular CB500/550s are known to easily foul their sparkplugs at idle. What - in theory - would make these CB Fours idle better: an electrode gap of 0,6mm or 0,7mm? Please motivate your answer.

Well we are not riding a model A ford that has 4:1 compression LOL so perhaps not as crude as you describe LOL. I have seen some "Hot Rod" type articles describing a "new" innovation introduced for V8 engines some of which had 2 valves and pushrods....and the "new idea" was present in early 1970's Japanese motorcyle engines :-).

I think a drop in system that had a crank trigger as well as providing an electronic advance curve would give the best bang for the buck for our bikes. Some DO exist but they are not hugely popular and some are not built on the same continent I choose to live on. Also in the mix is availability of electrons to run the coils that would be the simplest ones to use.

I do know that one person I follow on YouTube fried a couple aftermarket ECU, maybe Holley stuff by using copper core spark plug wires rather than the "resister" type. Not applicable to our bikes as made OEM but could crop up as an issue with a drop in system.

There are two things we face with these older bikes, advancers and springs, and points-condensers. The HondaMan system that I run eliminates the need for condensers and makes the points last a long time but they are still a finite resource currently.

Bill

🤔 I think Benelli SE1 has posted owning and/or is going to try a full straight up electronic ignition with selectable and/or custom electronic curves. Thus eliminating any mechanical components subjected to maladjustment, wear,  and age…
🤞

[Deltarider]

Back to the original question.

It would appear the correct plugs for a CB650Z are resistor plugs and the caps are also resistor caps, XD05F caps to be exact. This could be because unlike it's predecessors the CB500/550 it doesn't use points and condensers but a pulse generator system. The coils are also much different in having removable plug leads. Electronic coils tend to need higher resistance in the system so that may account for the 5K in the plug and in the cap, so 10K in total.

Then you must be the person that can explain why further identical bikes had different resistances in different countries. I advise you to consult Honda docs. Succes!
BTW, to me not clear what you mean by 'electronic' coil. A coil is electric. It's a quite primitive device and about the first thing the founding fathers of electricity came up with.

[Deltarider]

[...]

There are two things we face with these older bikes, advancers and springs, and points-condensers. The HondaMan system that I run eliminates the need for condensers and makes the points last a long time but they are still a finite resource currently.

Bill

No, his ignition does not eliminate condensers. Long before Hondaman, I've built a transistor ignition myself which works still flawlessly. Mine as well as Hondamans, definitely needs condensers either in the module or by using the stock condensers. IIRC Hondaman has experimented with leaving them out, but later advised his customers to use them nonetheless. For a reason. Mine are inside the box btw. Without any condensers you may have an even steeper rise time, but it comes at a price. Realise that you still operate mechanical breakerpoints which switch the control current and so - not dampened by a condenser - you run the risk of your power transistor producing multiple erratic firings which will not only cause an irregular, weaker ignition, but also will result in funny readings on an electronic tach and possibly useless erratic flashes of your stroboscopic timing light. The power transistor I have used, BU931P, can switch up to 500kHz! Out of curiosity I have tried my EI without condensers and although my bike ran almost as good, I was not quite satisfied, when I encountered forsaid symptoms.

[willbird]

it might be true that it is an urban myth.

as i read (over the years, in various forums),

Clearly you have been more succesful than me in finding other sources. I have knowledge of only one forum - for light pleasure aircraft - but that particular post was withdrawn later. The poster was identified by a member in this forum as the same person that has spread the theory of a longer spark duration in this here forum. It goes without saying I am interested to read what you have read.

the resistor is supposed to spread out the current flow over some more time, allowing for a longer duration of the spark, instead of a very sharp and instantaneous peak current, you supposedly have a longer 'plateau' current. sounds reasonable to me, but dont know if this holds up. [...]

What you describe here, fits the difference monitored in reality (!) between a CDI and a conventional or a non CDI EI. Some bikes benefit from CDI, some don't and there are bikes where it makes no difference.
As I see it, the combustion process in our oldfashioned engines is so utterly, utterly primitive that it will be quite a challenge to monitor a significant difference in performance when resistance in the secundary circuit is altered. As always I'm open to learn something new, but for now I stick with the advice NGK and Honda mechanics have given me. I've concluded that Canada must have had other legislation than elsewhere and I don't rule out batches that had that same noise suppression have been shipped to US and EU.
My gut feeling is that differences in gap of the sparkplug's electrode will give much, much more effect.
If you want to be sure you have enough spark duration, stick to the standard, by Honda prescribed gap, if you look for a somewhat higher voltage in the initial peak voltage, you may experiment with a slightly wider gap.
Here is a question for the experts. In particular CB500/550s are known to easily foul their sparkplugs at idle. What - in theory - would make these CB Fours idle better: an electrode gap of 0,6mm or 0,7mm? Please motivate your answer.

Well we are not riding a model A ford that has 4:1 compression LOL so perhaps not as crude as you describe LOL. I have seen some "Hot Rod" type articles describing a "new" innovation introduced for V8 engines some of which had 2 valves and pushrods....and the "new idea" was present in early 1970's Japanese motorcyle engines :-).

I think a drop in system that had a crank trigger as well as providing an electronic advance curve would give the best bang for the buck for our bikes. Some DO exist but they are not hugely popular and some are not built on the same continent I choose to live on. Also in the mix is availability of electrons to run the coils that would be the simplest ones to use.

I do know that one person I follow on YouTube fried a couple aftermarket ECU, maybe Holley stuff by using copper core spark plug wires rather than the "resister" type. Not applicable to our bikes as made OEM but could crop up as an issue with a drop in system.

There are two things we face with these older bikes, advancers and springs, and points-condensers. The HondaMan system that I run eliminates the need for condensers and makes the points last a long time but they are still a finite resource currently.

Bill

🤔 I think Benelli SE1 has posted owning and/or is going to try a full straight up electronic ignition with selectable and/or custom electronic curves. Thus eliminating any mechanical components subjected to maladjustment, wear,  and age…
🤞

There are a few out there, Benelli and I could walk towards each other and meet somewhere in the middle so we are on the same Continent :-).
There as far as I can tell are not any sold here that I have found yet, I'd be all over one if there was.

[Oddjob]

Back to the original question.

It would appear the correct plugs for a CB650Z are resistor plugs and the caps are also resistor caps, XD05F caps to be exact. This could be because unlike it's predecessors the CB500/550 it doesn't use points and condensers but a pulse generator system. The coils are also much different in having removable plug leads. Electronic coils tend to need higher resistance in the system so that may account for the 5K in the plug and in the cap, so 10K in total.

Then you must be the person that can explain why further identical bikes had different resistances in different countries. I advise you to consult Honda docs. Succes!
BTW, to me not clear what you mean by 'electronic' coil. A coil is electric. It's a quite primitive device and about the first thing the founding fathers of electricity came up with.

Because it's a requirement of that particular country??? Like the General Post Office in the UK said they must be suppressed to stop TV interference back in the 70s.

Electronic coil, a coil designed to run with electronic ignition rather than points and condensers, keep up at the back there.

[Tracksnblades1]

it might be true that it is an urban myth.

as i read (over the years, in various forums),

Clearly you have been more succesful than me in finding other sources. I have knowledge of only one forum - for light pleasure aircraft - but that particular post was withdrawn later. The poster was identified by a member in this forum as the same person that has spread the theory of a longer spark duration in this here forum. It goes without saying I am interested to read what you have read.

the resistor is supposed to spread out the current flow over some more time, allowing for a longer duration of the spark, instead of a very sharp and instantaneous peak current, you supposedly have a longer 'plateau' current. sounds reasonable to me, but dont know if this holds up. [...]

What you describe here, fits the difference monitored in reality (!) between a CDI and a conventional or a non CDI EI. Some bikes benefit from CDI, some don't and there are bikes where it makes no difference.
As I see it, the combustion process in our oldfashioned engines is so utterly, utterly primitive that it will be quite a challenge to monitor a significant difference in performance when resistance in the secundary circuit is altered. As always I'm open to learn something new, but for now I stick with the advice NGK and Honda mechanics have given me. I've concluded that Canada must have had other legislation than elsewhere and I don't rule out batches that had that same noise suppression have been shipped to US and EU.
My gut feeling is that differences in gap of the sparkplug's electrode will give much, much more effect.
If you want to be sure you have enough spark duration, stick to the standard, by Honda prescribed gap, if you look for a somewhat higher voltage in the initial peak voltage, you may experiment with a slightly wider gap.
Here is a question for the experts. In particular CB500/550s are known to easily foul their sparkplugs at idle. What - in theory - would make these CB Fours idle better: an electrode gap of 0,6mm or 0,7mm? Please motivate your answer.

Well we are not riding a model A ford that has 4:1 compression LOL so perhaps not as crude as you describe LOL. I have seen some "Hot Rod" type articles describing a "new" innovation introduced for V8 engines some of which had 2 valves and pushrods....and the "new idea" was present in early 1970's Japanese motorcyle engines :-).

I think a drop in system that had a crank trigger as well as providing an electronic advance curve would give the best bang for the buck for our bikes. Some DO exist but they are not hugely popular and some are not built on the same continent I choose to live on. Also in the mix is availability of electrons to run the coils that would be the simplest ones to use.

I do know that one person I follow on YouTube fried a couple aftermarket ECU, maybe Holley stuff by using copper core spark plug wires rather than the "resister" type. Not applicable to our bikes as made OEM but could crop up as an issue with a drop in system.

There are two things we face with these older bikes, advancers and springs, and points-condensers. The HondaMan system that I run eliminates the need for condensers and makes the points last a long time but they are still a finite resource currently.

Bill

🤔 I think Benelli SE1 has posted owning and/or is going to try a full straight up electronic ignition with selectable and/or custom electronic curves. Thus eliminating any mechanical components subjected to maladjustment, wear,  and age…
🤞

There are a few out there, Benelli and I could walk towards each other and meet somewhere in the middle so we are on the same Continent :-).
There as far as I can tell are not any sold here that I have found yet, I'd be all over one if there was.

Maybe BenelliSE1 will repost the ignition brand…when it was posted it came with several selectable curves and/or you could have a costomized curve. The all in by 2500 wasn’t a curve that came standard, as I read..

[Tracksnblades1]

Will bird,,

This may be the one…

https://www.elektronik-sachse.de/manuals/Z09-Ho-en.pdf

[willbird]

Will bird,,

This may be the one…

https://www.elektronik-sachse.de/manuals/Z09-Ho-en.pdf

Reading over the destructions it should work...$417.73usd or 392 Euro.