Topic: CDI Ignition

[AshimotoK0]

During the darkest days of recession of 1979 I was waiting around to see if my name had been put on the 'hit' list and everyone was sat around being miserable. I remembered seeing the unfinished remains of three car  CDI kits (Capacitive Discharge Ignition) someone had bought and never got to work based on a 'Practical Electronics' magazine design. lying around in a lab cupboard. I therefore decided to have a go at combining these into a dual unit for my 400/4, rather than sit around moping with the others. I got them working but they packed up after about 300 miles. The cause was two fold, the CDI storage capacitor was a ' standard' dielectric type and had gone 'short' so I replaced it with one from a colour TV HT circuit and likewise  the thyristor, which I upgraded to a 1200v version. It then went onto perform faultlessly for the 20k miles I kept the bike for, mounted in a diecast box placed where the 400/4 tool tray normally resides. For anyone who does not know about CDI it basically works like this. The 12v DC battery voltage  is 'inverted' to produce around 400Volts DC   and this charges up a capacitor. This 400v charge from this capacitor is then discharged across the the ignition coil 12v primary, which produces a really fat spark on the plug connected to the secondary  HT side of the coil. The discharging of the capacitor is triggered by the (standard) points and is controlled by a thyristor which is basically a solid state switching device

http://en.wikipedia.org/wiki/Thyristor

Does anyone make  a commercial CDI  unit like this today for our bikes? I particularly liked the fact that if the unit did fail, you could simply change back the the 'Kettering' points system  

http://en.wikipedia.org/wiki/Charles_Kettering

BTW I never did make it onto the 'hit' list!! But I was asked the move to Rockford in the USA (about 60 miles N of Chicago) which gets to -40F in the winter, so I declined and started my own business.

Cheers

Ash

[Steve_K]

Is that similar to Hondaman's ignition?  I have only heard good things about Mark's ignition thing.  Look for it in the for sale section.
Steve

[HondaMan]

Is that similar to Hondaman's ignition?  I have only heard good things about Mark's ignition thing.  Look for it in the for sale section.
Steve

Not yet. 

Mine is a simpler form, a transistor switch system that tunes the coils up a bit to improve their spark and stretch their range over more RPM. In the process, it reduces the current to the points to about 0.1 amp, and removes the characteristic arcing that so quickly eats points, thus letting them last a VERY long time with no wear or timing shift. It's the arcing/welding/breaking open pitting cycle that wears the pivots and feet on the points, not the opening/closing cycles. We are now seeing bikes with 5 seasons on these Transistorized Ignitions, with no timing shift at all. My own is a case in point: no timing adjustments needed since I installed it in early 2005.

In the development wings here is a form of CDI, but until I am happy with the reliability factors and a design that will fit the wide range of coils we see on these bikes, I won't be offering it to the 'public'. No one wants to push their bike home. 

CDI does not improve the engine performance (over a good Kettering setup with good parts) unless it is a multi-spark design. These types provide 2 or more sparks per cycle up to some moderate RPM, then fewer spark(s) until it drops to just one per cycle. Typical racing systems like these (MSD comes to mind) for cars can make up to 4 sparks to about 2500 RPM, 3 to about 4000 RPM, then 2 up to 6000 RPM, but can consume more electrical power to do it than these bikes can produce. Obviously, this is not much help on these high-revving bikes, which can surpass 10k RPM in many cases. The trick development here is to try to provide multi-spark capability without adding several amps to the bike's load: then there will be a net performance improvement. In such achievement lies a patent right.

[Steve_K]

I had supposed it was similar as to using standard points.  I am not very experienced in electronics, but Mark's points lasting much longer seems logical to me.  I hope to get my 750 going in 2011 and Mark's ignition will used.
Steve

[AshimotoK0]

The one I built way back in '79 was certainly reliable after initial teething troubles. It stayed on the 400/4 bike for 2 years and 20+k miles though grotty UK weather conditions as it was my only mode of transport to work etc. I used the standard Honda coils. I think some early Kawasaki 2 strokes used this principle too. I used to love the singing of the inverter when the ignition was on. I can't remember the current draw but it was not excessive. OK it drew current when the points were open but overall I think it was reasonable and certainly did not affect the bikes running. My points stayed like new for the two years it was fitted. I passed around 170 mA through them so that they would clean themselves electrically. It was still on the bike when I sold it. I just checked and that same bike (XDN 1**R) has just been UK 'taxed' until 2012 !!!!

May build one for my '69 750K0 using 'modern' components

Cheers

Ash

[xedge4lifex]

BTW I never did make it onto the 'hit' list!! But I was asked the move to Rockford in the USA (about 60 miles N of Chicago) which gets to -40F in the winter, so I declined and started my own business.

Cheers

Ash

rockford sucks, if you didnt move there you made a good choice. i spent 24 years in elgin about 30 miles east of there. everyone should avoid the midwest all together if you enjoy riding.

great piece im really looking forward to getting a cdi for my bike

[TwoTired]

Gerex used to make a CDI for the four cylinder wasted spark engines.
Wish I'd gotten one.  But, I didn't find out about them til after they quit making them.

You can find them used sometimes.  But, if they've been disused for a while, their capacitors go bad.  The capacitors (quality/longevity) are kind of the nemesis of the CDI system.

Having said that, if they see routine service they work well for a long time.  Witness my 72 Ford truck has had one in service since the late 70's.  Still works.  But, the box is 3x3x7 inches.  You'd need two of those for the SOHC4.

Cheers,

[DYSKORD]

I just got off the phone with Ken from Cyclex. He says that unlike the MSD ignitions, his produces multiple sparks through out the rpm range. Pretty interesting stuff.

[Gaither]

IMHO

Why make it complicated?

Just install a Hondaman Electronic Ignition Unit and forget it. Simple, proven reliablity, excellent warranty, easy to install. (If I can install one, anyone can!)

I sure enjoy mine! It is the very least of my concerns with the 550.

[a700guy]

This is a key statement "The trick development here is to try to provide multi-spark capability without adding several amps to the bike's load: then there will be a net performance improvement. In such achievement lies a patent right. "

Also add in that this is wasted spark, so Ken is popping off say 3 sparks at 9000rpm, asking alot to get that coil fully charged in wasted spark config in my opinion.

9000 rpm is his default rev limiter setting btw, on the advertised non user programable version, which they can change, at an additional cost, but you cannot, should you like this freedom, you will need to pay 80.00 more I believe it was, plus 120.00 I think it was for the cable and software.

Most stock 750's can run more than 9000, let alone a hopped up version.

this can be referenced here http://cyclex.yuku.com/topic/209/power-arc-curves

I ended up going with the dyna 2000 and their new compact coils and wires for right at 409.00, it is user programable should I choose, the cable only cost 100.00, there are a ton of features and settings.

JMHO

[AshimotoK0]

I run my own electronics design business and just for fun I am going to revisit this sometime as it was the late 70's when I designed that CDI for the 400/4. I agree the 400v storage capacitor is possibly the weak link but I did not have  aproblem there, it was the spec of the thyristor that had to be right. I ended up using a 1200v rated one, as I remember. If anyone has  a specification regarding the multi-spark variant then let me know and I will look into it. I noted at the time my mate got a CB400 twin and that had CDi (which failed after about 10k miles) so even Honda (or Hitachi) had problems there. The automotive environment is a very harsh one for electronics but it can be designed to be reliable (how many cars have points ignition now).

Rockford was described to me a 'a one Horse town'. However, whilst I was sat in the HoJo bar, biding away my time drinking 'Old Style 'beer ,little did I know then that it was the US home for Bridgestone bikes - I could have been out there finding one!! Everone there was friendly to me and I can't knock the mid-west.

Cheers

AshD

[malcolmgb]

I run my own electronics design business and just for fun I am going to revisit this sometime

does that mean you will not be sharing the drawing to build our own? 

[AshimotoK0]

I run my own electronics design business and just for fun I am going to revisit this sometime

does that mean you will not be sharing the drawing to build our own? 

Definitely not!!!!!  My living is earned from industrial electronics - the CDi is just part of my Hobby. I will glady put a circuit diagram on here done on Orcad, once it is done.

Cheers

Ash

[Deltarider]

Great! And after that you can move on to the development of the engineguard   http://forums.sohc4.net/index.php?topic=44306.msg461649#msg461649

[Gaither]

You can be glad  you're not in Rockford now. You would need a big shovel!

[Jerry Rxman Griffin aka MuthaF'er]

Gerex used to make a CDI for the four cylinder wasted spark engines.
Wish I'd gotten one.  But, I didn't find out about them til after they quit making them.

You can find them used sometimes.  But, if they've been disused for a while, their capacitors go bad.  The capacitors (quality/longevity) are kind of the nemesis of the CDI system.

Having said that, if they see routine service they work well for a long time.  Witness my 72 Ford truck has had one in service since the late 70's.  Still works.  But, the box is 3x3x7 inches.  You'd need two of those for the SOHC4.

Cheers,

Lloyd,

Do you think the NOS Gerex I have stashed in my basement will work on my Chop when I finally get it built? 

[TwoTired]

Gerex used to make a CDI for the four cylinder wasted spark engines.
Wish I'd gotten one.  But, I didn't find out about them til after they quit making them.

You can find them used sometimes.  But, if they've been disused for a while, their capacitors go bad.  The capacitors (quality/longevity) are kind of the nemesis of the CDI system.

Having said that, if they see routine service they work well for a long time.  Witness my 72 Ford truck has had one in service since the late 70's.  Still works.  But, the box is 3x3x7 inches.  You'd need two of those for the SOHC4.

Cheers,

Lloyd,

Do you think the NOS Gerex I have stashed in my basement will work on my Chop when I finally get it built? 

Probably not.    You should donate the hulk (Gerex not the chop) to me for evaluation testing. 
You wouldn't happen to have a schematic for it, would you?  That would go a long way toward keeping the unit in working condition.
Of course, if it is all potted into a solid brick, that would present a deterrent/challenge.  I've never seen one "in the flesh", so to speak.  Just the internet phantoms. 

Cheers,

[AshimotoK0]

Designed this in the early 90's and Patent for it is in my name and should have put one on my '69K0 but stuck with good old Nippon Denso for originality. They still make them in Shanghai . The later versions have data logging of motor temperature, run time, battery condition history etc which was read via a serial RS232 data link.

cheers!!

Ash - yes Rockford was freezing in the winter gets to -40 - I remember leaving my bag outside the 'Clock Tower Hotel' waiting for a shuttle bus to the airport. When I got to O'hare I tried to put my jeans on from the bag but they were frozen solid because of the moisture in the cotton. Here is a brain teaser for you -40 degrees F is also -40 degrees Centigrade !!  If you don't believe me work it out!!