Testing a CD Ignition System (CDI) on 1989 Mille, Now With Video of CDI on 9V

[Triple Jim]

As some of you know, I've been manufactuing CDI units for about seven years.  Most of them are for Kawasaki triples, and there are a few others for miscellaneous applications that have come up, like Porche 911s.  I've been resisting the temptation of making one for my Mille, because I didn't think I wanted to add unnecessary complexity.  The recent thread on transistor assisted ignition for Guzzis got me thinking about it again, and the advantage of nearly no points wear did seem attractive.

I know there are a lot of very knowledgeable guys on this board, but for those not familiar with CDI (Capacitor Discharge Ignition) systems, the principle is that a capacitor is charged with several hundred volts, and then connected to the spark coil's primary, repeating each time a spark plug needs to be fired.  This results in a very efficient generation of spark voltage, without needing to build up current in the coil by directly connecting it to 12v with the points. The efficiency is seen as reduced current consumption and reduced coil heating.  The available spark voltage is generally higher than with a stock points system, as well.

I already manufacture a CDI unit for Porche 911s that's points triggered, but it's a single points system for a car that has a distributor, and my Mille needs a dual system.  So I built two 911 circuit boards and fit them in the housing, which was a tight squeeze, but does fit fine.  The circiut has a very effective anti-bounce feature that ignores noise caused by the points bouncing after they close, which you can be sure they will try to do.  It's also potted, so vibration and moisture won't cause trouble.    

I've been bench testing it, and yesterday was able to install it on the Mille, and put about 30 miles on it before the snow arrived.  I set the timing accurately, using a piston stop and degree wheel, and made sure the advance was working as it should.  I also opened up the spark plug gaps to 0.040", or about 1mm.  The CDI unit has no trouble firing the larger gap, and a larger gap is more likely to light a mixture if conditions are borderline.

I know there are many opinions about ignition systems, and I don't intend to try to convince the points guys and the transistor assist guys that CDI is best.  I can tell you, however, that there are some advantages:

1. Starting my Mille when cold was noticeably easier.  It normally takes a couple engine revolutions to fire, but yesterday it fired almost immediately.

2. It's noticeably harder to stall.  It's obvious that if I let out the clutch too quickly, and pull the engine RPM down to something silly like 500, it just chugs along and recovers.  With points, it would be likely to stall.  I attribute this improvement to the fact that when points open very slowly, they tend to arc, losing the sudden opening of the circuit, and the associated rise in coil primary voltage.  With the CDI unit, when the points open very slowly, rather than the output to the coil suffering, it becomes a rapidly repeated series of sparks.

3. I set the current through the points to 50 milliamps (0.050 amps).  This should be high enough to prevent the "dry switching" problems of very low contact current, but low enough to reduce point wear to near zero.

4. The 12 volt current requirement to the CDI unit is very low.  When first turned on, it is 0.6 amps, and remains at that level when the engine is idling.  The current increases approximately linearly to redline, when it's 1.1 amps.  I'm used to seeing up to around 2 amps with other engines like a Kawasaki triple, but the number of sparks per second for a Guzzi engine is about 1/3 of what a 2-stroke 3-cylinder engine needs, so the current requirement is lower.  Compared to 3Ω coils and points, that leaves about 3 amps of alternator output available for other things like battery charging.

I'll put some more miles on the system and update the thread with anything I learn.  I'm using a smaller than stock AGM battery, and since I had already mounted Bosch blue coils in the front of my battery tray, I mounted the CDI unit where the stock coils were originally mounted.  Here are a couple photos, first of the mounting plate that bolts to where the coil clamp used to attach, and next of the mounted CDI unit.  I'm not sure yet where the CDI unit would fit if coils are mounted in the original location.  I left all of the original wiring intact, so that if the CDI unit fails, I can reconnect things to be a stock points system.  I don't expect it to fail though, since this circuit has proven to be very reliable in other applications.  The CDI unit was designed to work well with either points type coils with 3Ω-5Ω primaries, or CDI specific coils with less than 1Ω primary resistance.

[Kiwi_Roy]

Good on you ;-T
So a single points setup like my Ambo would be just on CDI, correct?

[Triple Jim]

Correct, Roy.  It would be essentially the same as the Porsche 911 unit I've been selling.

[redrider90]

How about moisture. How is it sealed?

[Triple Jim]

It's potted in epoxy potting compound, Harvey.

[redrider90]

Jim,
I hope this post is not overwhelming but I know so little about how ignitions work. I see a lot of hype (I am not suggesting you are hyping anything) and now that you opened Pandora's box I thought I might learn a bit. I read and watch what you do like the whole thing with the coils and found you are willing to try anything and have the electrical engineering back round to prove it so here are a few questions. I am a layman with it comes to ignition systems.
What makes your CDI  so popular in the Kaw triple crowd? I know you started making them because your own an H2. It sounds like you have done a good business with the the old triples. Did they have particular shitty ignition systems. I think of how weak the ignition was on my 72 Duck. I put freaking huge black Chevy coils on it and it ran a whole lot better back in those days it all I had.
Also as  laymen I am trying to understand what the advantage of the CDI is over basic points to coil to spark plug.   Years ago I put in Dyna + 3 ohm coils. Note they do not recommend the 3 ohm anymore with the Dyna. I suffered multiple failures over the next 35K miles but not nearly as bad as the stock motoplat. Luckily I was always near home.
But back to basics for someone who knows enough to install a points dizzy and add a dyna to it and tune it properly. But after that I know nothing about what is in that little black box Dyna makes and has failed on me as well as 3 coils.  I like the blue bosch set up cause it seems economical and you added some ohms which reduced heat and amp draw off the charging system. Anything I can do to add amps on my Mille is  a +. And if my 3 ohm green Dyna coils are failing do to heat then maybe looking at adding 1-2 ohms would help?  You can by 2 blue bosch coils for 1/2 of dyna coils.
But it sounds like the CDI actually is like a middle man in the system: building up power to make it more efficient/powerful dump into the coils. It also reduces draw on the battery and reduces the power through the points extending the life of the points.
But am I correct that a CDI unit like the one you describe is what an amplifier of sorts? It also sounds like you are claiming the you are getting more power to the coils cause it does not stall at 500 rpms in 1st gear.
 Maybe a lot to ask but I don't understand much about CDI stuff and I always thought the Dyna was a CDI and now I think it is not a CDI: correct.  I assume the stinking motoplat was also not a CDI?

[kckershovel]

    Is this something that could be modified to work standalone with a later efi engine. Say if someone wanted to put carbs on  an engine that no longer has the hole for the distributor?

 

[Triple Jim]

Jim,
What makes this unit so popular in the Kaw triple crowd? I know you started making them because your own an H2. It sounds like you have done a good business with the the old triples. Did they have particular shitty ignition systems. I think of how weak the ignition was on my 72 Duck. I put freaking huge black Chevy coils on it and it ran a whole lot better back in those days it all I had.

The problem with the triples is that the 40+ year old electronic parts are nearing their end of life.  Capacitors in particular are subject to age related failures.  The original CDI systems that were used in the triples are actually very good.  The magneto CDI units I make are copies of the originals used on the later triples, with more robust components.  My 12V CDI units are of a newer and less complicated design than the originals that came on the early H1s.
 

Also as  laymen I am trying to understand what the advantage of the CDI is over basic points to coil to spark plug...  ...But am I correct that a CDI unit like this is like an amplifier on its own? And it also sounds like you are claiming the you are getting more power to the coils cause it does not stall at 500 rpms in 1st gear.

The Kettering system, which is the simple points and coil system, gets a current flowing in the coil primary by connecting it to the 12V battery through the points.  At the right time, the points open and cut off the current flow.  Like all inductors, the very inductive primary winding of the coil doesn't like to allow sudden changes in current, so it develops a high voltage in an attempt to keep the current flowing.  At least that's one way of looking at it.  This high primary coil voltage is then multiplied by the many more turns of wire in the coil's secondary, and sent to the spark plug.

A CDI system charges a capacitor to a few hundred volts, and electronically connects it to the coil primary when triggered, in this case by points opening.  The points are now just a sensor to tell the CDI circuitry when to fire the coil.  So it's not assisting the points, nor is it amplifying what the points do, it's just using the points to signal when to make a spark.

Maybe a lot to ask but I haven't read much about CDI stuff and I always thought the Dyna was a CDI and now I think it is not a CDI. I assume the stinking motoplat was also not a CDI?

I don't have personal experience with either system, but from what I've gathered, I think you're right, that both systems use a transistor to do the job that the points did, and turn the transistor on and off with the points.  In this case, the ignition unit really is amplifying a low level signal from the points, and switching the current to the coil on and off like the points used to do.  This reduces the current through the points to a signal level, extending their life.

    Is this something that could be modified to work standalone with a later efi engine. Say if someone wanted to put carbs on  an engine that no longer has the hole for the distributor? 

Nate, that's a reasonable question, but this CDI unit has no provision for an advance curve, since it is triggered by the original distributor that has the advance mechanism built in.  So it would require adding electronic advance to make it useful for what you want.  It would also need to be triggered by a magnetic pickup or Hall effect sensor (etc.) or something that provides a signal telling the unit when to fire.  Crankshaft sensing would be OK, but would result in a wasted spark system, so ideally it would sense cam position.  Building a custom system like this is probably more involved and expensive than just starting with an engine that has a distributor.

[redrider90]

A CDI system charges a capacitor to a few hundred volts, and electronically connects it to the coil primary when triggered, in this case by points opening.  The points are now just a sensor to tell the CDI circuitry when to fire the coil.  So it's not assisting the points, nor is it amplifying what the points do, it's just using the points to signal when to make a spark.

So If my Dyna box crapped out on me again, could I mate your CDI to the Dyna sensor without any problems or would the Dyna sensor require a different CDI than the kind with the points?  I still have the points set up that came with the used Dizzy. I
Also could this CDI be used on the Motoplat sensor? After all the problem with the Motoplat on the Milles and Callis was not the sensor but the boxes that failed. There are 2 boxes on the Motoplat. Each one controls a coil. I call them boxes because they are not CDI but the WTF are they? It is those units that had a very high rate of failure.

[Triple Jim]

So If my Dyna box crapped out on me again, could I mate your CDI to the Dyna sensor without any problems or would the Dyna sensor require a different CDI than the kind with the points?

Another one I make that's triggered from a magnetic pickup would probably work with the Dyna sensor, but I'd have to make some measurements to be sure.

Also could this CDI be used on the Motoplat sensor?

The Motoplat distributor doesn't have the parts to create the advance curve, so I'd have to to that electronically.  I will probably work on that at some point, but I don't currently have anything with advance built in.

[Triple Jim]

I put another 50 miles on the CDI today.  It's definitely easier to start and keep running when cold.  It also clearly takes less revving and clutch slipping when maneuvering around my uneven, hilly, and currently soft gravel driveway.

I measured the "break-even" charging RPM with my LED headlight and two standard 1157 tail light bulbs lit, and it is about 1,300 RPM.  When I first got this Mille and it had the quartz-halogen headlight bulb and 3Ω Dynatek coils, break-even was around 2,800 RPM, so I'm much happier with the battery charging situation now.  

It freely revs to redline without any misfiring, but it did that with the stock ignition system too, so I can't  claim an improvement there.  Similarly, I don't expect a miraculous improvement in gas mileage, but I'm keeping track of it.

It looks like starting this Saturday, the weather should settle down to about what's normal here, which means I can put in test miles a lot easier.  Testing is a good excuse to go for a ride when I should be working, so that's another improvement I just thought of.

[boatdetective]

Jim-
Sounds very intriguing.

I have a V50III witha  Dyna S sytem to Dyna coils. I think I have a bum coil.  I'm wondering if your CDI will improve things any. Is this the type of a thingama jiggy that we could plug into our existing systems between the sensor and the coils?

[AJ Huff]

I love this kind of stuff!   ;-T

-AJ

[Triple Jim]

I have a V50III witha  Dyna S sytem to Dyna coils. I think I have a bum coil.  I'm wondering if your CDI will improve things any. Is this the type of a thingama jiggy that we could plug into our existing systems between the sensor and the coils?

As I understand the Dyna S, the whole thing is contained under the distributor cap, and the wires that come out go to the coils and other things like an electric tach.  This means if you used the Dyna S as a sensor to trigger a CDI unit, you'd still have it in the system with the CDI unit.  That doesn't sound like the best setup for reliability, with two systems running like that, and if either one fails, the engine stops. 

I think the V50 III came with points, so if you configured the distributor back to stock, then this CDI unit would work fine, triggered by the points, and if the CDI unit failed, you could pull over and plug the points directly into the coils, and get back on the road, minus CDI.

My intention for making this CDI unit was to get its benefits without going to the trouble or expense of modifying the distributor.  You still have the mechanical points, but their life is greatly extended, and if the electronics fail, it doesn't leave you stranded.

I love this kind of stuff!   ;-T

-AJ

Can you tell that I do too?   :D

[Triple Jim]

I just took a look at the Dyna III system.  It appears to have a sensing unit in the distributor, and the main ignition unit mounted separately.  It's likely that one of my other CDI units would interface to that sensor and work well, but I'd have to get a Dyna III in front of me to find out.

[redrider90]

I put another 50 miles on the CDI today.  It's definitely easier to start and keep running when cold.  It also clearly takes less revving and clutch slipping when maneuvering around my uneven, hilly, and currently soft gravel driveway.

50 miles is kind of meager ride for you Jim. Did those day long 30 MPH crosswinds bring back home a bit sooner?  :D

[Triple Jim]

50 miles is kind of meager ride for you Jim. Did those day long 30 MPH crosswinds bring back home a bit sooner?  :D

The weather was actually about as good as it gets, but the little woman was in town getting groceries, and I didn't want to leave Dad alone very long.  I hope things are OK at your end.

[redrider90]

The weather was actually about as good as it gets, but the little woman was in town getting groceries, and I didn't want to leave Dad alone very long.  I hope things are OK at your end.

I had some sheets of roofing tin flying around and had to secure them before they came through the window or hit a parked car. No trees down. One more storm tomorrow.
Right know we are on the edge of it but who know what the forecast will be in the morning.

[Triple Jim]

Wow, you had way worse wind gusts than we had here.  Let's hope tomorrow is not bad.

[Rough Edge racing]

 Jim, US V8 tuners avoided single spark CD ignitions claiming they have a very short duration spark. And aftermarket CD's didn't catch on until MSD got into the business with multi spark units in the 1980's. Of course now every after market ignition seems to be a multispark billion volt CD unit.
   Kevin Cameron and other bike tuners have also mentioned to short spark duration as not the best for 4 strokes....
 But here you are selling these for Porsches  and if they didn't work they wouldn't sell......And noticing an improvement in your Guzzi's performance...
  Good for you  ;-T

[Triple Jim]

Actually this one can be configured for multispark or single spark.  I built the one on my Mille as a single spark unit to learn if that's enough, and it certainly does seem to be.  With the multispark configuration, current consumption is a little higher, and I'm reasonably sure the spark plug electrodes would erode faster.  I hate to go in that direction because it's the popular thing to do, if there really aren't any real-world benefits on these engines.  I'm sure that some of the more extreme (racing) engines could benefit from multispark.

I wish I hadn't had that one set of points develop the loose shaft and let the points move all around, forcing me to change them.  I would have left the timing as it was to see if the tendency for detonation changed.  I was getting a little pinging on high throttle before, and now I'm not, but since I reset the timing to spec, I can't know the whole reason for the reduced pinging.  

When I was testing a system for early Kawasaki H1s, my beta tester had a prototype CDI unit that was not producing its best spark at high RPM.  It's not trivial to get a CDI unit to spark well 500 times per second.  He closed the plug gap from 0.040" to 0.025" and reported that the high RPM running was improved, but he was then getting some detonation.  This seems to be proof that spark intensity and plug gap can effect combustion to some extent, and it may well be that my reduced detonation is due to the CDI's higher spark current and larger plug gap.  I suppose I can reconnect the wires to go back to stock, set the plugs back to 0.025" and see if the pinging returns.

[Rough Edge racing]

 Jim, I messed with multispark CD ignitions on auto engines and the advantage is primarily in severe situations. Like supercharged or nitrous or firing mixtures messed up at low speeds by radial cams. The multispark shortens plug life somewhat...Almost all the multi sparks go single spark above 3-4 thousand RPM's. Probably at higher speeds there's not enough time or it's not needed....And the multi sparks play hell with fancy digital timing lights...Most bikes, especailly older ones with carbs,run rich enough at low speeds making the mixture easy to fire anyways..
  You gonna market them?

[Triple Jim]

I appreciate hearing your experiences with multispark CDI.  I think you're right about most units going to single spark at high speed because it's hard to maintain good multispark when things start happening fast.

I'll probably add them to my web site at some point, since there seems to be a real improvement over the stock points system.  In the past I've been kind of hung up on the idea that I had to eliminate breaker points, but I'm liking the fact that by plugging the wires from the points directly into the coils, I can go back to stock very quickly.  Even if the electronics never fail, it's comforting to know I wouldn't be stranded if they did.  I still need to solve the problem of where and how to mount the unit if the coils are kept in their original location.

[Triple Jim]

I put another 140 miles on the CDI Mille today.  Nothing new to report other than the additional test miles.  I guess that's good.   :)   It sure feels nice riding in mid 60s air temperatures after what we've gone through this winter.

[Triple Jim]

Another 100 miles today and nothing special to post about.  I guess I'll call this thread wrapped up, test successful, and leave the CDI unit on the Mille long-term.

[Triple Jim]

I thought I was finished with the thread, but I decided to see how the CDI unit would work with a partially discharged battery.  I used six AA cells, giving 9 volts to power it, and made a video:

https://www.youtube.com/watch?v=UVnEA0a3IKU&feature=youtu.be

[redrider90]

I thought I was finished with the thread, but I decided to see how the CDI unit would work with a partially discharged battery.  I used six AA cells, giving 9 volts to power it, and made a video:

https://www.youtube.com/watch?v=UVnEA0a3IKU&feature=youtu.be

Jim,
We all know a standard electronic ignition will fail to run an engine at 9V. Will a standard points ignition run an engine on 9 volts? I must say that is pretty damn cool idea to set it up with 9 Volts to show its performance. So you could easily push start your bike @ 9V battery.

[Triple Jim]

Some points systems will probably do better with low voltage than others, depending on the specifics.  My experience with the ones I have is that they get pretty marginal when the voltage gets low.  My Ford 4000 tractor gets hard to start if the battery is low enough that the cranking is slow.

Earlier today I cranked the Mille engine in the garage, with a plug lying on the valve cover, and it sparked with four AA cells powering the CDI unit, so I decided I'd actually try running it on low voltage.  It seemed pretty much like when it's on full battery voltage with the six AA cells (9v).  It's not in the video, but it ran on four AA cells (6v) too.  I could tell the spark was weak though, because if I gave it throttle suddenly, it hesitated before it caught.

[redrider90]

Some points systems will probably do better with low voltage than others, depending on the specifics.  My experience with the ones I have is that they get pretty marginal when the voltage gets low.  My Ford 4000 tractor gets hard to start if the battery is low enough that the cranking is slow.

Earlier today I cranked the Mille engine in the garage, with a plug lying on the valve cover, and it sparked with four AA cells powering the CDI unit, so I decided I'd actually try running it on low voltage.  It seemed pretty much like when it's on full battery voltage with the six AA cells (9v).  It's not in the video, but it ran on four AA cells (6v) too.  I could tell the spark was weak though, because if I gave it throttle suddenly, it hesitated before it caught.

So your charging system fails and this CDI would take you further (not to mention that you run a LED headlight) than  stock points?? as well as electronic ignitions. Shoot you were pulling 9V offer flashlight batteries and it was running just fine. What happens when you run up the RPMS? Does it consume more power.
What about comparing the power consumption of your CDI to the C5 optical unit on 9 V?

[Triple Jim]

What happens when you run up the RPMS? Does it consume more power.

At 12v (really 14v) it stays under 1 amp until I'm near the redline at 7,000 rpm, when it's about 1.1 amps.  At 9v, the current consumption was lower, like under 1/2 an amp from idle to 3,000 rpm.

What about comparing the power consumption of your CDI to the C5 optical unit on 9 V?

I really don't know anything about that system, sorry.  My goal really wasn't to show off, it was to find out how the CDI unit would behave with low input voltage on an engine, but when I saw it appearing to work fine at 9v I thought I'd better make some evidence.   :)
  I do have a spark plug with a 5mm gap, to simulate the difficulty of sparking with fuel and compression when bench testing, but it's only an approximation.