Author Topic: Embarrassing ignition question  (Read 818 times)

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Offline desertrefugee

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Embarrassing ignition question
« on: February 13, 2022, 02:49:29 PM »
OK guys, I’m gonna open the kimono here and ask for help.  Got the carbs squared away and installed  on my planet blue K5 and went to fire the thing up for the first time. In fact it’s been cold and dark for 10 years.

But I’m only firing one of the coils.  Points should make it simple, huh?  What I’m seeing is ~7 ohms resistance on the blue side points to ground when the points open up.  Pretty sure it should be wide open with the points open. (Like the yellow side is).  It’s not coming from the coil primaries although it sure seems it would be based on the reading I’m getting.  My next step is to run a temporary jumper to the blue wire from the points up to the coil. My thinking is that I may have a pinched wire in that line.

I have spent the better part of two hours trying to figure this out. I am embarrassed that it’s not intuitively obvious to me, but I’m going to chalk it up to chemo fog.

Anybody have an idea of what I might be missing or overlooking?
« Last Edit: February 13, 2022, 02:53:01 PM by desertrefugee »
'86 Vmax, '83 ZN1300, '78 GL1000, '75 CB750 K5, '78 F4

Offline BenelliSEI

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Re: Embarrassing ignition question
« Reply #1 on: February 13, 2022, 03:02:55 PM »
Is the plastic “top hat” insulator installed correctly where the wire attaches to the points?

Offline Don R

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Re: Embarrassing ignition question
« Reply #2 on: February 13, 2022, 03:29:19 PM »
    What he said. ^
No matter how many times you paint over a shadow, it's still there.
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Offline desertrefugee

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Re: Embarrassing ignition question
« Reply #3 on: February 13, 2022, 05:32:08 PM »
Hmm.  I will focus on that and report back.  I was only getting fire on the left side right out of the box. In other words, I didn't mess with the configuration until I knew I had problems with it.

Thanks guys.
'86 Vmax, '83 ZN1300, '78 GL1000, '75 CB750 K5, '78 F4

Offline Don R

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Re: Embarrassing ignition question
« Reply #4 on: February 13, 2022, 05:51:57 PM »
 I had a set of points with a worn-down rubbing block. It would run OK from time to time, I replaced the points and it's been ok since then.
No matter how many times you paint over a shadow, it's still there.
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Offline Tracksnblades1

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Re: Embarrassing ignition question
« Reply #5 on: February 13, 2022, 05:57:39 PM »
^
^
Attached is a picture of the insulating washers used
to allow the points to complete the circuit. In stead of
a horse shoe type wire end or point spring end doing
so a little early. Those of us with eyes over 40 and only
20/20 at best may have been guilty of this. I check with
 a magnifier now days…😜

My old 76f coil 1-4 will stop firing around 6.5 volts.
While 2-3 coilwill fire down to 5.5 volts. I have 12volts now
after cleaning the connectors in those circuits..😁
« Last Edit: February 13, 2022, 07:06:10 PM by Tracksnblades1 »
Age Quod Agis

Offline HondaMan

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Re: Embarrassing ignition question
« Reply #6 on: February 13, 2022, 06:38:18 PM »

But I’m only firing one of the coils.  Points should make it simple, huh?  What I’m seeing is ~7 ohms resistance on the blue side points to ground when the points open up.  Pretty sure it should be wide open with the points open. (Like the yellow side is).  It’s not coming from the coil primaries although it sure seems it would be based on the reading I’m getting.  My next step is to run a temporary jumper to the blue wire from the points up to the coil. My thinking is that I may have a pinched wire in that line.


Umm...by chance, do you have Daiichi condensors? I have seen this with them within 10 minutes of being installed. That's how bad they are. They condensors are VERY poorly made. I haven't seen a single one work for more than 3-5 minutes on a brand-new Daiichi points plate, since about 2014. They are the definition of pure Chinko crap.

I use mostly old TEC or Hitachi condensors (some from old junkyard points plates) as they never really "wear out". After 40 years they drop a little in capacitance, usually to their lower tolerance limits of 0.20uF, but they still work and will [very] slowly restore themselves with regular use - like daily commuting service. This is one of the big diferrences between 'condensors' and 'capacitors', with the other being condensors are able to completely charge and discharge at constant rates over temperatures better than capacitors, all else being equal.
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline desertrefugee

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Re: Embarrassing ignition question
« Reply #7 on: February 13, 2022, 07:48:11 PM »

But I’m only firing one of the coils.  Points should make it simple, huh?  What I’m seeing is ~7 ohms resistance on the blue side points to ground when the points open up.  Pretty sure it should be wide open with the points open. (Like the yellow side is).  It’s not coming from the coil primaries although it sure seems it would be based on the reading I’m getting.  My next step is to run a temporary jumper to the blue wire from the points up to the coil. My thinking is that I may have a pinched wire in that line.


Umm...by chance, do you have Daiichi condensors? I have seen this with them within 10 minutes of being installed. That's how bad they are. They condensors are VERY poorly made. I haven't seen a single one work for more than 3-5 minutes on a brand-new Daiichi points plate, since about 2014. They are the definition of pure Chinko crap.

I use mostly old TEC or Hitachi condensors (some from old junkyard points plates) as they never really "wear out". After 40 years they drop a little in capacitance, usually to their lower tolerance limits of 0.20uF, but they still work and will [very] slowly restore themselves with regular use - like daily commuting service. This is one of the big diferrences between 'condensors' and 'capacitors', with the other being condensors are able to completely charge and discharge at constant rates over temperatures better than capacitors, all else being equal.

Thanks Hondaman.  I have no idea which condensers are installed.  All bits were already in place - and appear new.  I immediately suspected a condenser issue since they're parallel across the points, but it's currently doing what "capacitors" do.

I'll reassess the installation tomorrow and go from there.  I have a used Dyna unit in my box o' stuff, but would probably go with another complete new points setup first.

Thanks for the leads so far.  Will get back soon...   (should have been a slam dunk)
'86 Vmax, '83 ZN1300, '78 GL1000, '75 CB750 K5, '78 F4

Offline HondaMan

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Re: Embarrassing ignition question
« Reply #8 on: February 13, 2022, 07:59:18 PM »
If you think points are trouble...you'll think they are great after a Dyna S, IMHO...
I've replaced a bunch (5 or 6) of Dyna S units with points in the last 7-8 years, and magically "fixed" the bikes in the process. :(
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com

Offline desertrefugee

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Re: Embarrassing ignition question
« Reply #9 on: February 13, 2022, 09:46:44 PM »
I removed the points plate for my 78 GL 1000 and installed a Dyna S about eight years ago. I haven’t looked back. Never a flicker. 

They were a bit of a pain to get timed properly because the mass of the unit itself prevented adequate range of motion for adjustment. As I recall, I split the difference in timing with two sides. Bike runs like a Singer sewing machine.
« Last Edit: February 13, 2022, 10:40:55 PM by desertrefugee »
'86 Vmax, '83 ZN1300, '78 GL1000, '75 CB750 K5, '78 F4

Offline HondaMan

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Re: Embarrassing ignition question
« Reply #10 on: February 14, 2022, 07:05:50 PM »
I removed the points plate for my 78 GL 1000 and installed a Dyna S about eight years ago. I haven’t looked back. Never a flicker. 

They were a bit of a pain to get timed properly because the mass of the unit itself prevented adequate range of motion for adjustment. As I recall, I split the difference in timing with two sides. Bike runs like a Singer sewing machine.

Yeah, the GL bikes have large alternators and can feed the 2.5x over normal current load caused by the Dyna S. The SOHC4 bikes, not so much. :(
See SOHC4shop@gmail.com for info about the gadgets I make for these bikes.

The demons are repulsed when a man does good. Use that.
Blood is thicker than water, but motor oil is thicker yet...so, don't mess with my SOHC4, or I might have to hurt you.
Hondaman's creed: "Bikers are family. Treat them accordingly."

Link to Hondaman Ignition: http://forums.sohc4.net/index.php?topic=67543.0

Link to My CB750 Book: https://www.lulu.com/search?adult_audience_rating=00&page=1&pageSize=10&q=my+cb750+book

Link to website: www.SOHC4shop.com