Topic: Ignition Analysis: Honda's coils

[HondaMan]

Aren't 79 750 DOHC4 coils lower ohm coils?

OOPS! I missed the "79" part of his message! 

Yes, they would require resistors. Sorry!

Those DOHC coils require the 2 ohm resistors, which cost a few bucks more than the standard 1 ohm parts.
Sorry, didn't mean to mislead.

[papp101]

Thanks hondaman! I saw you put a link up somewhere to a place that would sell resistors fit to this application. Could you post that one, or can I just grab a set at Radioshack? (do I need 1 for each coil, or just splice one in before the two wires are split?)

[HondaMan]

Thanks hondaman! I saw you put a link up somewhere to a place that would sell resistors fit to this application. Could you post that one, or can I just grab a set at Radioshack? (do I need 1 for each coil, or just splice one in before the two wires are split?)

I sell a specially-built Resistor Pack for these bikes, in 1 ohm ($12.50) and 2 ohm ($17.50) versions (plus shipping). You can make your own by getting the parts from Allied or Digi-Key or Mouser: Radio Shack doesn't usually handle them. You need a 1 ohm for 3-ohm coils, 2 ohm for 2-ohm coils, in 10 watt size, with some form of mounting that will keep the heat away from the gas tank and fuel lines.

[ascanio1]

Hello HH,

Here we should not post questions so I apologize if this contains the request for advice and is not 100% specific to the thread. I would like to upgrade the electrical system on my K3 since points are complicated to maintain (for me) and poor tuning affect performances and reliability.

I wish to improve 1) reliability, 2) simplicity of maintenance and, if possible, 3) performances. Would you, please, spare some time and expertise to advise me on what can be reasonably done?

Please use moron proof layman's language as I read the whole thread looking for a layman's language post, up to post #78, but not finding it, I gave up! A repair shop near in Tokyo will do the upgrade, so it's not DIY but in Japan any modification from the stock/manual is very strongly discouraged and, therefore, I can't ask: "what can I reasonably do to modernize the electric system?"

Thanks in advance for any advice.

In Italy I have a Riva Aquarama wooden runabout boat from 1969 with 2 crusader (GM 454) motors with that period's similar electrics. Every week I needed an electric repairman to fix something: I finally replaced all the system with modern alternator, distribution, ignition etc... and I wish I had done it earlier!

[GammaFlat]

Ignition and Charging System are closely coupled.  Unfortunately, it's very hard to ignore that fact.  The problem is that the charging system in CB750's (I assume your K3 is a 750) is not "bountiful".  Things like 40 year old connections, headlights that consume more power than OEM and accessories exacerbate the "problem". 
Changing to an electronic ignition (e.g. Dyna) is a consideration.  You may like the fact that you've eliminated points maintenance but you pick up other issues: extra power consumption, non-ideal spark curve, charging and discharging characteristics of the coils, etc. 
The original points are engineered to make the bike run a certain way but most agree that their maintenance is a problem with the "grass is greener" electronics available on newer bikes, boats and cars. 
The best compromise (opinion alert) is to use HondaMan's ignition.  It is very low overhead when it comes to power consumption and makes your properly set up points last forever.  Set them and forget them. 
Your "coupled" issues of charging and ignition are both addressed very nicely with this solution. 

[ascanio1]

@ gammaflat,
First of all thanks for using layman, simple terms. This is the first post that I understand in the thread!
 
Cost (within reason) is not an issue but reliability, maintenance-free and performance are. Keeping these points (no pun intended) in mind, is HH's the most reliable, maintenance free and performance-friendly solution to my problem?

@ HH,
I would appreciate your view/reply. Before gammaflat's reply I sincerely did didn't understand and - perhaps - your whole thread is already about my very issue and I simply did not realize it. I am happy to install a completely new system or upgrade mine with your system or others: my objective is reliability and ease of maintenance (w/ performances, if possible).

[GammaFlat]

@ gammaflat,
First of all thanks for using layman, simple terms. This is the first post that I understand in the thread!
 
Cost (within reason) is not an issue but reliability, maintenance-free and performance are. Keeping these points (no pun intended) in mind, is HH's the most reliable, maintenance free and performance-friendly solution to my problem?

I don't know the current cost of a HondaMan ignition but I believe it to be cheaper than competing solutions (e.g. Dyna, Pamco).  In terms of reliability, I think it would be hard to beat the HondaMan ignition.  The fundamentals of how it works tell the tale...

The way we get spark is by charging up a coil and suddenly collapsing the field in the coil which makes the "charge" want to escape.  The easiest path (to escape more or less) we give it is across the electrodes of a spark plug.  The switching required to accomplish this rapid charging and discharging of the coil is done by the points. 

When using the HM ignition, we are "re-purposing" the points.  We ask the points to "tell us" when to perform this switching which is now performed by the HM ignition.  So the responsibility of the points is changed so that they now "signal when" to switch on and off the coils (very low burden) instead of carry the heavy burden of performing the switching (lots of "juice").  This is why the points will likely never wear out or need to be touched/adjusted again after they're set up properly the first time when using the HM ignition. 

We have the points reliability problem solved now.  How about the reliability of the HM ignition itself... (which is the other major component in this system)?  I don't know what exact components are used but I do not hear of any failures and I would suspect it is generously spec'd in terms of reliability.  In the odd event that it did fail, you can switch back to "regular points" in five minutes on the side of the road. 

The performance issue is addressed elsewhere on this forum but I'll give you a few things to chew on.  The retro-fitted electronic systems (e.g. Dyna and Pamco) do change how long the coil charges and correspondingly how long the coil discharges (relative to points setup).  These "durations" become especially important at high rpm and can impact performance... My money is with the original Honda engineers and you get their intent if you use the HM ignition. 

You'll also definitely notice more favorable cold starts and cold idling.  This is probably true of any of the ignition upgrade options. 

The HM ignition is probably the least invasive of the bunch.  You don't need to remove the points plate as you do with the others.  You add a small box to your bike and make some wiring changes. 

Good luck!

[ascanio1]

@ GammaFlat,

Thanks, I really appreciate your time because I understood almost everything. I still don't understand one point, which does NOT relate to HM's system but to modern Vs points systems.

If I understood correctly, modern electrical systems as I installed on my boat (not HM's system), without points, perform worse at high rpm than the original 70s Honda setups, with points. In other words I have to trade reliability for performances. Did I understand correctly?

Hm's system, instead, would allow better reliability without performance loss. Right? Something to do with the fact that the points are better at timing the spark compared to a modern ignition system. But if this were the case why today we don't use points anymore?

[HondaMan]

Some of the weak points of aftermarket all-electronic ignitions are:

1. Less "Off" dwell as compared to the points, which translates to weaker spark at high RPM. An example of this is the Dyna S unit, which has about 30 degrees "Off" dwell as compared to points, which are 180 degrees "Off" dwell. A longer "Off" dwell allows a longer time for the spark to discharge at the sparkplug. If this dwell is too short, the spark is interrupted when the fast-moving electronics stops that "Off" dwell and starts charging the coil again, instead of letting the coil fully spark.

2. All-electronic ignitions use considerably more electrical power than do points. Again looking at the Dyna S: it uses 1.25 amps more power than points, due entirely to the very short "Off" dwell time. Any all-electronic ignition with less than 180 degrees of "Off" dwell will also use correspondingly more power from the alternator. For example, if an electronic system uses 120 degrees of "Off" dwell, the extra power it will use, as compared with points, is:
(180 degrees-120 degrees)/180 degrees * 100% = 33.3% extra power used.
For the Dyna S, with its short 30 degrees "Off" dwell, this is:
(180 degrees-30 degrees)/180 degrees * 100% =  83.3% extra power used.

This "extra power used" is simply wasted power from the bike's alternator.

3. All-electronic systems are nice IF they are reliable: if they fail, you are stuck on the side of the road, looking for a truck to ride home.

My Transistor Ignition addresses these 3 items this way:
1. The points switch the Ignition, which in turn switches the coils, so the "Off" dwell is EXACTLY the same as what Honda engineers designed. This means stock coils, points, and condensors can still be used. The main difference: this unit stops all the arcing at the points, so they stop wearing and last a VERY long time without adjustment.

2. My unit uses precisely 0.1 amp extra power, as compared to points alone. All of the SOHC4 bikes (and most Honda twins and singles) can manage this extra power easily. This translates to 3.8% extra power used.

3. This Transistor Ignition has a special feature not found on any all-electronic ignition: if the box should fail for any reason, you can easily unplug the 4 wires from the box that connect to the points and coils, and plug the points and coils back together, in about 5 minutes or less, using no tools. This immediately puts you back on the road, using the points as originally designed. (I did this on purpose with this unit, just in case...) 

One other feature not often talked about with the Transistor Ignition is its ability to monitor the temperature of the points and adjust the coil drive accordingly. What this means to you is: when the engine is cold, the spark is stronger to assist in starting. When it is hot, the power is slightly reduced to the coils so they run cooler, but since the transistors switch faster than the points did, the spark is still stronger, and longer duration, than with points alone.

The SOHC4 engine, in particular, LIKES having a long-duration spark, because it is a swirl-charge design. A longer spark lights a wider flamefront inside the engine, thus producing a more complete burn and a longer 'push' on the piston for each cycle. Most riders notice the power improvement from this, right away.

[ascanio1]

Thanks HM,

I appreciate the time and explanation and I will ask my mechanic to install your system.
 
But how did technological progress overcome this problem in all-electronic ignition systems?
Today engines do not use points, they use all-electronic ignition systems, so some solution must have been found.

[HondaMan]

Thanks HM,

I appreciate the time and explanation and I will ask my mechanic to install your system.
 
But how did technological progress overcome this problem in all-electronic ignition systems?
Today engines do not use points, they use all-electronic ignition systems, so some solution must have been found.

Yep, today's all-electronic systems are very different from the old ones, and they use correspondingly more electrical power to accomplish it. Modern bikes (1980 and newer) have typically alternators TWICE the power of our SOHC4 bikes, which is a major player in making the later systems work well.

For example, the most common modern systems (since 1980 or so) are CDI type. These devices charge up a [large] capacitor with a BUNCH of electrical power, then launch it through a [very different sort of] coil at spark time to generate the arc. This makes a short, hot spark that was once thought to help reduce emissions. (In truth, the lack of poor points maintenance had far more to do with that part of it...) The engine designs had to change to work well with this short-duration spark, often changing the combustion chambers to a semi-hemi shape with high-dome pistons and DOHC top ends to tightly control the intake charge, which has been the shape of things since then.

As time continued, coil technology got better enough that the electronics can directly manipulate the spark duration desired. Ford started this approach in 1990, now it is common on even bikes. As the engine runs slower, the spark may happen up to 3 times in one combustion cycle in these newer systems, reducing emissions and improving low-end torque. For the hi-winding 'Busa-like bikes, a much hotter spark that jumps a much longer gap is needed, because at speeds over 10k RPM there isn't enough time to fire multiple sparks, so those types of bikes have gone that direction instead of multi-spark (they don't have all that much low-end attraction, anyway, say their marketers.   ).

But, these fancy electronic systems are power-hungry critters. A typical multi-spark systems uses about 6-8 amps of power (an SOHC4 uses 2.4 amps in comparison) while the hotshot versions can use up to 11 amps. Most cars after 1998 or so use 20-28 amps for their systems, a far cry from the old points-and-coil Ford/GM 2.8 amp systems we old guys grew up with!

[ascanio1]

What can I say? WOW!

Very nice of you to take your time to explain such interesting info!  Now I understand perfectly why your system cannot be rivaled by modern upgrades unless you upgrade also the alternator and ruin the bike's originality, value and character.

Please don't take my advice the wrong way but why don't you explain both the background (technological progress) and the content itself in a brief introductory phrase, simple and generic, without using technical terms/jargon? Something like:
"My system preserves originality, increases reliability and reduces maintenance w/out affecting performances (or improving it) compared to more modern technology aftermarket electronic upgrades (like Dyna S) because these require alternators with double the power (which our bikes can't deliver) to preserve performances. So you either upgrade the whole electric system with post 1980's hardware or you use my system.

This would have caught my, and other "electric ignorant" owner's, attention because it's easy to understand and while it's beneficial to you but, more important, it's also beneficial to those non-mechanical-savvy for whom your system is even better suited since they don't know how to delve into points & ignition repairs as expert forum members can. I'm glad that I took a few days to "dig" into your thread and ask explanations (kindly answered)!

I called my boat yard in Italy and they confirmed that - in fact - they changed also both alternators. Riva Historical Society allows these upgrades without detracting points at shows because of safety reasons: it's quite different to be stuck in the middle of the Mediterranean sea rather than the side of a road.  I have linked the President of the Riva Historical Society to your system and I hope that it will contribute to make our Riva runabouts safer and more reliable, while keeping everything original.

Thanks HM, I wish you a sparky new 2015! 

[HondaMan]

What can I say? WOW!

Very nice of you to take your time to explain such interesting info!  Now I understand perfectly why your system cannot be rivaled by modern upgrades unless you upgrade also the alternator and ruin the bike's originality, value and character.

Please don't take my advice the wrong way but why don't you explain both the background (technological progress) and the content itself in a brief introductory phrase, simple and generic, without using technical terms/jargon? Something like:
"My system preserves originality, increases reliability and reduces maintenance w/out affecting performances (or improving it) compared to more modern technology aftermarket electronic upgrades (like Dyna S) because these require alternators with double the power (which our bikes can't deliver) to preserve performances. So you either upgrade the whole electric system with post 1980's hardware or you use my system.

This would have caught my, and other "electric ignorant" owner's, attention because it's easy to understand and while it's beneficial to you but, more important, it's also beneficial to those non-mechanical-savvy for whom your system is even better suited since they don't know how to delve into points & ignition repairs as expert forum members can. I'm glad that I took a few days to "dig" into your thread and ask explanations (kindly answered)!

I called my boat yard in Italy and they confirmed that - in fact - they changed also both alternators. Riva Historical Society allows these upgrades without detracting points at shows because of safety reasons: it's quite different to be stuck in the middle of the Mediterranean sea rather than the side of a road.  I have linked the President of the Riva Historical Society to your system and I hope that it will contribute to make our Riva runabouts safer and more reliable, while keeping everything original.

Thanks HM, I wish you a sparky new 2015! 

I've always sort of been a "let the product tell the story" kind of guy, I guess?
I disbelieve 99% of the claims out there by anyone who makes stuff, because so often they take some minor point and blow it all out of proportion to what it really does, then sell it on that item. In that regard, it sure worked out OK here: I thought I would build maybe 50-100 of these back in 2006 and that would be the end of it. Instead, there's thousands of them all over the world, now, running everything from outboard (boat) motors to old farm tractors, vintage cars, trucks, and motorcycles (single, dual, and triple-points versions). I'm afraid to advertise! I probably couldn't keep up with it, then.

One salient point, though: it actually does improve performance. While I knew how it changed the system overall, I just let everyone else 'figure it out' when they install it, instead. The reasons are many, but few non-electronics riders understand them, so I don't usually elaborate. Instead, I think everyone should just hit the road with them, and enjoy the bike!   That's what I do!

[ascanio1]

That's also a good philosophy... but that's not how Mr. Bosch, Mr. Phillips or Mr. Lucas became who they were...

If an idea does not have any real advantage, you can advertise it as much as you like but it will never take off. Conversely, also if an idea does have a real advantage, but you don't "sell" it (advertise)...  it can be as good as you like but it still will never take off...
I'm no electronic technician, so my opinion does not count but, if the idea is as good as it seems, then you are wasting an opportunity by not advertising it and you're just waiting for a smart entrepreneur to steal your idea and make money...

Patent it, then go on to Web site called kickstarter and ask for funding or, better, a business partner to launch your product.

In periods of recession good idea stand out much more... anyway, your chances to become the next Mr. Bosch start here.

Also I have a philosophy. Mine is related to girls, but you can apply it to your idea too: if you want to sleep with a top model, then the chances of succeeding to get under the sheets with her will increase dramatically if you ask!


Sent from my SM-N9005 using Tapatalk

[ascanio1]

Anyway, my bike is going to the shop at the beginning of Feb and I asked John (mechanic) to install it...

[FunJimmy]

This has been a very interesting and insightful thread, albeit I found it a tad late. On my CB550, I'm currently using a Pamco ignition with Dyna 5 ohm coils and Denso Iridium plugs. There was a recent thread selling the merits of multi spark so I purchased a fancy schmancy C5 (Power Arc) multi spark system. Now I'm confused and uncertain it was the right choice.

[Retro Rocket]

This has been a very interesting and insightful thread, albeit I found it a tad late. On my CB550, I'm currently using a Pamco ignition with Dyna 5 ohm coils and Denso Iridium plugs. There was a recent thread selling the merits of multi spark so I purchased a fancy schmancy C5 (Power Arc) multi spark system. Now I'm confused and uncertain it was the right choice.

The power arc was on cycleX's giant killing 750/4 {915cc} race bike that demolished everything in its path, so I wouldn't be too worried Jim...

[HondaMan]

This has been a very interesting and insightful thread, albeit I found it a tad late. On my CB550, I'm currently using a Pamco ignition with Dyna 5 ohm coils and Denso Iridium plugs. There was a recent thread selling the merits of multi spark so I purchased a fancy schmancy C5 (Power Arc) multi spark system. Now I'm confused and uncertain it was the right choice.

Is there a power (amperage) requirement provided by CycleX for that Power Arc system? The CB500/550 bikes can only provide a maximum of 3.2 amps for the entire Ignition system (total), and this is only if you remove the front running lights, run without the headlight unless you are above 3500 RPM (i.e., hiway riding), and change the taillight bulb to a #1034 lamp. Most of the Mid-Fours only make a real 110 watts of power available overall.

[scottly]

There was a recent thread selling the merits of multi spark so I purchased a fancy schmancy C5 (Power Arc) multi spark system. Now I'm confused and uncertain it was the right choice.

Jimmy, when I, as well as others, tried to ask pertinent questions on that thread, you were among those that basically told us to shut up. BTW, inductive systems like the C5 are generally incapable of generating multiple sparks at higher RPMs, due to the short dwell time after the initial spark.

[Retro Rocket]

There was a recent thread selling the merits of multi spark so I purchased a fancy schmancy C5 (Power Arc) multi spark system. Now I'm confused and uncertain it was the right choice.

Jimmy, when I, as well as others, tried to ask pertinent questions on that thread, you were among those that basically told us to shut up. BTW, inductive systems like the C5 are generally incapable of generating multiple sparks at higher RPMs, due to the short dwell time after the initial spark.

So after saying all that Scott, how come it works so well..?  You may need to buy a C5 to prove the rest of what you say.. The Cycle X race bike spanked all in its way and set some pretty hard to break records, if these digital ignitions are so bad, why do they work so well...?

[FunJimmy]

Jimmy, when I, as well as others, tried to ask pertinent questions on that thread, you were among those that basically told us to shut up. BTW, inductive systems like the C5 are generally incapable of generating multiple sparks at higher RPMs, due to the short dwell time after the initial spark.

That's bull#$%* Scottly and you know it! Your questioning was bordering on hostile and that's what I took exception to. Paul answered questions thoroughly and completely.

[savior70]

There was a recent thread selling the merits of multi spark so I purchased a fancy schmancy C5 (Power Arc) multi spark system. Now I'm confused and uncertain it was the right choice.

Jimmy, when I, as well as others, tried to ask pertinent questions on that thread, you were among those that basically told us to shut up. BTW, inductive systems like the C5 are generally incapable of generating multiple sparks at higher RPMs, due to the short dwell time after the initial spark.

So after saying all that Scott, how come it works so well..?  You may need to buy a C5 to prove the rest of what you say.. The Cycle X race bike spanked all in its way and set some pretty hard to break records, if these digital ignitions are so bad, why do they work so well...?

Gotta believe Ken and the boys at cyclex. They know their chit. Peace!

Savior69

[scottly]

Since the new guy decided to pick the scab off the wound, go back and read through the cyclex race bike thread; there were ignition issues, IIRC? Something about using the ignition off the rider's street bike??
Let's crunch some numbers... The Power Arc, in C5 form, has 100* dwell at 3900 RPM, but the second spark happens only 15* later. This leaves only .6405 ms for the coil to both discharge and recharge, far less than the 1.3ms spark duration that Mark has measured on the stock system. As the RPM increases, the situation gets worse, as things like inductors only care about time, not degrees or RPMs. At 7800, that 15* would be .32025 ms.
One of the questions Paul was asked was did the multiple spark feature have an upper RPM limit, and the response was that it had been tested to 14,000 RPM(?), but didn't actually mention how it was tested or the results of said tests.  He also mentioned that he wouldn't post any dyno results, as he had been suspected of manipulating the results on other forums.    
 

[seanbarney41]

There was a recent thread selling the merits of multi spark so I purchased a fancy schmancy C5 (Power Arc) multi spark system. Now I'm confused and uncertain it was the right choice.

Jimmy, when I, as well as others, tried to ask pertinent questions on that thread, you were among those that basically told us to shut up. BTW, inductive systems like the C5 are generally incapable of generating multiple sparks at higher RPMs, due to the short dwell time after the initial spark.

So after saying all that Scott, how come it works so well..?  You may need to buy a C5 to prove the rest of what you say.. The Cycle X race bike spanked all in its way and set some pretty hard to break records, if these digital ignitions are so bad, why do they work so well...?

Gotta believe Ken and the boys at cyclex. They know their chit. Peace!

Savior69

yeah, Ken does know his #$%*.  After witnessing the CycleX superbike DNF at Gingerman raceway, I asked him what happened.  He said...probably ignition failure.  Yes, the bike bike was about 3 seconds (well, it was way) ahead at about mid race when the ignition failed.  So yeah, it was very fast.  I am curious what the new owner of the bike has been up to with it.  Anybody know?

[calj737]

Since the new guy decided to pick the scab off the wound, go back and read through the cyclex race bike thread; there were ignition issues, IIRC? Something about using the ignition off the rider's street bike??
Let's crunch some numbers... The Power Arc, in C5 form, has 100* dwell at 3900 RPM, but the second spark happens only 15* later. This leaves only .6405 ms for the coil to both discharge and recharge, far less than the 1.3ms spark duration that Mark has measured on the stock system. As the RPM increases, the situation gets worse, as things like inductors only care about time, not degrees or RPMs. At 7800, that 15* would be .32025 ms.
One of the questions Paul was asked was did the multiple spark feature have an upper RPM limit, and the response was that it had been tested to 14,000 RPM(?), but didn't actually mention how it was tested or the results of said tests.  He also mentioned that he wouldn't post any dyno results, as he had been suspected of manipulating the results on other forums.    

Actually, the C5 has 3 sparks, not 2 per cycle. They also use their specific coils, so comparing their performance to stock Honda coils and citing that as a baseline for unreliable performance claims is irresponsible.

Their website clearly states the system has rev limiter capabilities, and that the system has been tested beyond 10,000 RPMs. For 99% of street riders on a SOHC, they will never bump into the rev limits as the motor red lines below that number. I remember the question being posed to Paul about upper limit testing, and his polite reply was "as high as 14,000". I think it safe to assume they had success at that level, else he would have said "up to xx,000" don't you think?

Simply because the CycleX bike blew up and was running a PowerArc, does not verify that the PowerArc is a bad product. In fact, CycleX's choice and confidence in running is a pretty strong testimony. Okay, maybe it failed. But why? And can you honestly say a product for the street that can't withstand very hi-PO drag racing isn't up to running your street bike? That's absurd- Drag racing breaks motors, frames, transmissions, and anything else you bolt to a bike.

And lastly, Paul's comment about dyno results was "I've stopped posting our dyno results as they have been accused of being manipulated due to their impressive results".  I think that's pretty honest actually. But how many people buy Dyna or Pamco systems without dyno graphs?