Spark units


Jmichaelb
New Member & Happy To Be Here
New Member & Happy To Be Here
Posts: 5
Joined: Sun Feb 26, 2017 5:18 pm
Location: Mooresville Indiana
Location: Mooresville Indiana

Re: Spark units

Post by Jmichaelb »

My thoughts also. It was my father's bike so at the first sign of trouble I shut it down. Sounds like it's gonna be down for a minute until I can source the money to fix it.

Jmichaelb
New Member & Happy To Be Here
New Member & Happy To Be Here
Posts: 5
Joined: Sun Feb 26, 2017 5:18 pm
Location: Mooresville Indiana
Location: Mooresville Indiana

Re: Spark units

Post by Jmichaelb »

I would rather change it all. It was my father's bike so breakdowns make me a nervous wreck. Thanks

Pridanc
ICOA Member
ICOA Member
Posts: 6
Joined: Thu Feb 13, 2020 9:39 pm
Location: Austin, TX
Location: Austin, TX

Re: Spark units

Post by Pridanc »

Hey folks, I realize that I'm revisiting an old issue but as I'm new to the CBX scene felt I should ask this as I've not seen it addressed.
My OE boxes are beginning to leak the tar as seen in the picture. I've yet to fire the bike but will shortly (assuming of course these parts still work) but wanted your thoughts. Assuming these units continue to work, do I just deal with the tar leaking out or is there a "fix" for this? As in re-potting them with something or? Baring that, assuming again it all works, I'm not needing any better performance so perhaps just replacing these with the ones available from Ricks? Or should I just "bag" it and install the Dyna system that TIMS sells?
Thanks in advance, Sincerely, Price

daves79x
ICOA Technical Director
ICOA Technical Director
Posts: 4000
Joined: Sun Oct 01, 2006 8:05 am
Location: Knox, PA
Location: Knox, PA

Re: Spark units

Post by daves79x »

Your spark units are very likely OK. Many guys just clean them up the best they can and re-pot using a variety of materials. I've used black silicon, others have used various epoxies. Search that here, I think you'll find details.

Dave

User avatar
CBX-tras
ICOA Member
ICOA Member
Posts: 49
Joined: Tue Feb 16, 2010 2:29 pm
Location: Clinton Twp, Michigan
Location: Clinton Twp., Michigan, USA

Re: Spark units

Post by CBX-tras »

Since the time that this post was initiated a few years ago, many of us are using the Ignitech system. Replaces the ignitors and provides mapping capabilities far beyond the normal, stock ignition.

Pridanc
ICOA Member
ICOA Member
Posts: 6
Joined: Thu Feb 13, 2020 9:39 pm
Location: Austin, TX
Location: Austin, TX

Re: Spark units

Post by Pridanc »

Thanks for all the info guys.

Another thought: Does it make any sense to replace the spark units with the ones Rick sells, or better to make the jump to Ignitech? The bike does not have to stay OE but I'm also OK with it being stock so long as it is reliable. Sadly I am a tech junkie but trying to break the "must have it" itis if there is no real reason to do so.

Since all I really want to do is ride, I'm leaning towards the easier (lazier) route of Ricks spark units if you guys think those are good and reliable.

All opinions are welcome and thanks to all of you in advance.

divan
ICOA Member
ICOA Member
Posts: 25
Joined: Thu Jun 21, 2012 5:58 pm
Location: La Crosse, Wisconsin, USA
Location: La Crosse, Wisconsin, USA

Re: Spark units

Post by divan »

Just for reference: The potting Honda used to weather-seal these units is a type of epoxy commonly used as an electronic sealant at the time. I’ve tested it on an old unit and it begins to soften and flow at around 360 degrees F. It does not “wear out” over time – only excess heat causes it to flow. One culprit on the 79 CBX is the way it’s mounted stacked with the regulator, which can get very hot, especially if the heat sink fins are dirty and clogged or the regulator is failing. May be why Honda separated the spark unit from the regulator on the later models. But that’s about the only ambient condition that could do it. The other culprit is the transistor units themselves. It’s common to see only one or two of the OKI pods with potting melted out, and that’s a likely sign that the transistors in those pods are overheating. Lots of things can cause the transistors to overheat, including starting/running on a low battery or other conditions that alter input voltage parameters to the transistor circuits, failure of one or more of the surface mount capacitors they used on these boards, etc.. And melted potting doesn’t necessarily mean the units are bad – the heat may have only been temporary, not long enough (as with low battery running) to permanently damage the units. But at this point in their lives age is likely the main problem. These units employed 4 bi-polar transistors, in a surface mounted IC, and it’s not uncommon with really old transistors to see the silicon dopants used to create junction values in the transistors diffuse over time and alter the values (voltage, in this case), causing the units to continuously overheat.
Dick Sullivan

Larry Zimmer
ICOA Web Post/Pix/Video Archive Mgt
ICOA Web Post/Pix/Video Archive Mgt
Posts: 1713
Joined: Mon Dec 15, 2003 3:32 pm
Location: Brighton, MI
Location: Brighton, Mich
Contact:

Re: Spark units

Post by Larry Zimmer »

Good info, Dick. Many thanks from/for all of us. This might suggest, to me, that if you see much 'gooy stuff', it might be a thought to look for replacements. Obviously, with transistors, they don't give 'warnings' and have a 'reserve' position.
Larry Zimmer
cbxlarry@sbcglobal.net

divan
ICOA Member
ICOA Member
Posts: 25
Joined: Thu Jun 21, 2012 5:58 pm
Location: La Crosse, Wisconsin, USA
Location: La Crosse, Wisconsin, USA

Re: Spark units

Post by divan »

My thought too. These OKI units were remarkably robust, with a pretty good tolerance for low/high voltage inputs. But of course they're really old now. OKI primarily manufactured electronic switching stuff for telecommunications (motorcyle switches were a really small subsidiary for them in the 70's), so I guess they knew how to make them reliable and tough. One other weakness in the spark units, though, is only minimal protection from momentary back EMF pulses from the coils. The only protection in the circuit is a Zener diode, which only blocks part of the pulses. Modern transistor ignitions use more thorough shunt circuits to bleed pretty much all of the EMF away from the transistor circuits. The Zener circuit is another likely source of transistor degradation.
Dick Sullivan

divan
ICOA Member
ICOA Member
Posts: 25
Joined: Thu Jun 21, 2012 5:58 pm
Location: La Crosse, Wisconsin, USA
Location: La Crosse, Wisconsin, USA

Re: Spark units

Post by divan »

This risks hijacking the original thread, so I'll stop with one other curiosity. I'm always curious about this kind of stuff -- been working with it since I was a kid. A few years ago I bought some OKI pods on E-Bay just to find out what "lived" inside one of those pods. (The ones I bought were, like a lot of stuff on E-Bay, clearly junk, so I wasn't removing good stuff from circulation). Here's a photo of the circuit board after cleaning the internal sealant off a bit. Most folks won't care what it looks like, but some of us may.
Looking at this setup is kind of interesting historically. It wasn't "state-of-the-art" for its time (mid 70's); rather it was pretty much industry standard transitioning from mechanical switching to semi-conductors, and so it's a mix of older and newer gadgets. Today, all of this stuff can be made in one chip that is microscopic in size. So this is really a museum piece by modern standards. :-)
Dick Sullivan

divan
ICOA Member
ICOA Member
Posts: 25
Joined: Thu Jun 21, 2012 5:58 pm
Location: La Crosse, Wisconsin, USA
Location: La Crosse, Wisconsin, USA

Re: Spark units

Post by divan »

Sorry -- here's the photo:
You do not have the required permissions to view the files attached to this post.
Dick Sullivan

User avatar
Jeff Bennetts
Posting God
Posting God
Posts: 1795
Joined: Wed Mar 05, 2003 9:38 am
Location: Ohio, USA
Location: Ohio, USA

Re: Spark units

Post by Jeff Bennetts »

Thanks for posting that!

Larry Zimmer
ICOA Web Post/Pix/Video Archive Mgt
ICOA Web Post/Pix/Video Archive Mgt
Posts: 1713
Joined: Mon Dec 15, 2003 3:32 pm
Location: Brighton, MI
Location: Brighton, Mich
Contact:

Re: Spark units

Post by Larry Zimmer »

"Museum piece" is right, Dick! Wow! Quite interesting. The fact that many of them are still functioning is quite a tribute to someone.
Larry Zimmer
cbxlarry@sbcglobal.net

Post Reply

Return to “ELECTRICAL: Alternator, Batteries, Headlights, Switches, Tailights, Wiring....”