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At flaming last !!!

PostPosted: Mon Apr 23, 2012 7:04 am
by Kool_Biker
Some of you may have followed my 'Spark units ... on the way out' post.

Unhappy with the idea of just replacing the ignition unit (I have a 79), to see IF one or more of the ignitors was/were the problem, AND unable to borrow a unit locally to swap, I decided to look deeper into my CBX ignition circuits, and take some measurements.

So the bike was connected to an external fuel tank, a gentle fan was placed in front of it, and my old and trusty oscilloscope came out!
P1110002.jpg

The lower oscilloscope beam was connected to the 1&6 cylinder coil (low tension side), and the upper one to the 3&4 (middle coil).
At the start everything looked good with the ignitors firing the coils at 120' intervals as they should. But as the bike (and presumably the ignitors) warmed up the 3&4 ignitor began firing intermittently, all over the place! Eureka!!!
P1110026-2.jpg

This was 100% consistent with my experience of a properly behaving bike when cold, and then the 'pinking' as I opened the throttle when warmed up (but still no idea why the 'pinking' seemed to go away after ~4K RPM.
I also loved how the sound of the engine changed as the spurious pulses came on and off. Made so much sense.

So, my 3&4 ignitor is 'on the way out'. Or is it?
Theoretically of course, it could be the pick up coils so my next step is to swap the contacts in the two out of the 3 ignition connectors to verify that the 3&4 ignitor is 100% at fault and not it's pick up coil(s).

Not in a rush and so if any one has a similar experience, PLEASE chip in.

Best, (a very happy) Aris

Re: At flaming last !!!

PostPosted: Mon Apr 23, 2012 9:21 am
by Jeff Bennetts
Aris, good find and makes perfect sense.

Just curious Aris, are you keeping a journal of all the trails and tribulations along with your solutions concerning your CBX?
I think it would be cathartic for you and informative and entertaining for any CBX enthusiast.

Keep us posted and good luck,
JB

Re: At flaming last !!!

PostPosted: Mon Apr 23, 2012 10:30 am
by Kool_Biker
Jeff Bennetts wrote:Just curious Aris, are you keeping a journal of all the trails and tribulations along with your solutions concerning your CBX?
I think it would be cathartic for you and informative and entertaining for any CBX enthusiast.

JB


To date, a 159 A4 pages Word document, with hundreds of pictures ... :techie-typing:
With all I've seen and done on this bike today, "cathartic" would be an understatement.
But, ... I love every minute of it! And frankly I would be nowhere without all you people know how, mentoring and support. :text-thankyouyellow:
Aris

Re: At flaming last !!!

PostPosted: Mon Apr 23, 2012 10:38 am
by Larry Zimmer
Aris, I believe that YOU have become our incredible on-line resource. Most educational and beneficial. Thank you, my (our) friend.

Re: At flaming last !!!

PostPosted: Tue Apr 24, 2012 6:23 am
by Kool_Biker
Well ... before running to replace my ignition system, I thought I would have a closer look at the parasitic firings of ignitor 3,4.

Not content with hit and miss snapshots (see earlier pic above) and as I do not have a proper data logger, I pointed my little Panasonic camera on my analogue scope, and took a short film while revving the engine. On inspection and going at it frame by frame I found something quite interesting:

ALL spurious (parasitic) firings of ignitor 3,4 are triggered by legitimate firings of the other two!
Sooooo could it be a case of marginal wiring, grounding and +12V in particular, rather than the ignitor itself? Or could it be a case of one of the trigger coils or HT coils on the way out making the ignitor more sensitive to interference?

Can't wait to take a few careful measurements tonight, AND double check the wiring of the ignition unit itself. This is one of the few things left unturned by me on this bike :sad-roulette: and as you can see from the pic below, it has been "attended to" before.
DSC02846.jpg


Quick question: What is the easiest way to remove the ignition unit from a 79? Seems hard and I do not want to have to take half the bike to bits, for no reason :?

Keep you posted.
Aris

Re: At flaming last !!!

PostPosted: Tue Apr 24, 2012 11:47 am
by daves79x
Aris:
Remove the rear inner fender and access is OK from there - not great, but it can be done.

Dave

Re: At flaming last !!!

PostPosted: Tue Apr 24, 2012 12:50 pm
by Kool_Biker
daves79x wrote:Aris:
Remove the rear inner fender and access is OK from there - not great, but it can be done.

Dave

Yes, great tip Dave.
I also found removing the chain guard as well (easy), access becomes even better.
Cheers, Aris

Re: At flaming last !!!

PostPosted: Thu Apr 26, 2012 2:43 am
by Kool_Biker
Well my friends, I stand defeated.
After spending 2 evenings going through every nook and cranny of the original ignition system on my 79, I have given up and just ordered a Dyna S from TIMS.

Problem was (and still is) spurious firing of ignitor 3,4 at 1,6 & 2,5 intervals, a form of cross talk.
Cross talk by poor grounding and / or the puny switched +12V wiring was suspected at first. Both these lines were reinforced with quality wiring, direct to the battery with no change what so ever.
Then the Honda HT coils were checked, found to be within tolerances (2.8 Ohms primary, 21.5 K Ohms secondary with resistive caps on) AND were changed as a matter of course with NOS, again with no improvement.
Next the trigger coils were checked. All 3 were, again, within spec at ~500 Ohms, all 3 producing nice clean pulses at their outputs to the ignitors.
Finally the ignitors themselves were removed from under the battery tray, disassembled, visually inspected (ugly), then connected up and set on the top of a stool next to the bike. With the engine running and my scope connected all over the place, I could not markedly improve the situation.
P1110030.jpg

The final blow was when I discovered a tiny bit of spurious firing of ignitor 2,5. :sad-roulette: This was the point at which I decided to accept defeat.

My take, the OKI units, all 3 of the old runny tar type have deteriorated to the point that they are no longer protected well enough from spurious electrical pulses, in and in proximity to them. May be some of the capacitors in the units have drifted or otherwise deteriorated, who knows. This is very consistent with the fact that the problem only manifests itself when the engine is hot.

So, time to focus my energy on my other trusty steed, my GL 1000, as the weather here is unbelievable!
And I do hope (and know, he is a great guy) Bill will not delay my Dyna S.
Hope I haven't bored everyone here.
Aris

Re: At flaming last !!!

PostPosted: Thu Apr 26, 2012 7:24 am
by Rick Pope
Bored? Absolutely not. I've found your threads informative and entertaining. The pictures alone are worth the price of admission.

Re: At flaming last !!!

PostPosted: Thu Apr 26, 2012 7:45 am
by NobleHops
What he said, many thanks for the contributions to the knowledge base Aris.

N.

Re: At flaming last !!!

PostPosted: Mon Apr 30, 2012 6:44 am
by Kool_Biker
Hi all and over the moon!
My Dyna S has just arrived from TIMS (record time, thanks Bill!) and in the process of installing.
Does anyone have a picture of the magnetic trigger, installed on a 422 advancer, NOT 469?
Just making sure I get it right as the DYNA provided info is so scant ... and these little springs ...
Cheers
Aris

Re: At flaming last !!!

PostPosted: Mon Apr 30, 2012 7:47 am
by NobleHops
I went through this. The instructions suck. Stand by while I search...

Re: At flaming last !!!

PostPosted: Mon Apr 30, 2012 7:34 pm
by Quickster2
If you get some better instructions please let everyone know and share. The instructions are very poor. I just wasted time and money finding out that these Dyna units are not compatible on a 469 advancer. Yes, my '80 still had a 469 advancer. After time, money, and frustration, procured a 469A advancer and after reviewing the service bulletins and set-up instructions relative to the original warranty campaign(s) were finally able to get the Dyna installed and the advance curve verified. Maybe my experience was not typical but if one sells a product the product info. should be more robust.

Re: At flaming last !!!

PostPosted: Mon Apr 30, 2012 8:16 pm
by daves79x
I would think you would want to chuck the 469 advancer anyway. They were clearly inferior and recalled way back in the day. But whole-heartedly agree, the instructions for the Dyna are pretty poor. Everyone seems to get it, eventually, but you'd think they would be clearer.

Dave

Re: At flaming last !!!

PostPosted: Tue May 01, 2012 6:22 am
by Kool_Biker
NobleHops wrote:I went through this. The instructions suck. Stand by while I search...


Thanks Nils, I have now managed to install and time successfully.

I should have taken some pics, but I simply was too impatient. And it's all good!

Best, Aris