Author Topic: Help! Have 12.6 volts from blue and yellow coil wires.  (Read 1127 times)

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Offline Snider1970

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Help! Have 12.6 volts from blue and yellow coil wires.
« on: January 08, 2024, 01:54:01 PM »
I have an m.unit blue and using stock switches.  I am also using stock coils.  I had the bike timed and running before starting my rebuild.  In the process of doing the fine tuning on the bike, I started to install my Dyna S ignition.  When I went to static time it I found I had a constant light on both the blue and yellow wires.  Not just when the timing marks matched.
According to the Dyna instructions it is usually an indicator that there maybe a bad connection.
So, I take my volt meter and start testing voltage.  I have 12.6 volts in my ignition wire from the output side of my m.unit to the switch.  Turning on the switch I have 12.6 volts from the switch to both coils.  I then test the blue and yellow wires that connect to the points AND I CONSISTANTLY HAVE 12.6 V THERE TOO! 
Now I am stumped.
This is obviously not an new problem on these bikes because Dyna knew of it, but there is NOTHING out there to troubleshoot it.
So, if there are some YouTube Channels looking for content here's a topic.
« Last Edit: January 09, 2024, 05:31:52 PM by Snider1970 »

Offline Snider1970

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Re: Help! Have 12.6 volts from blue and yellow coil wires.
« Reply #1 on: January 09, 2024, 05:37:34 PM »
This is happening before the points were removed.  Now that the points are out I still have this issue.  I do not want to plug in and possibly blow my Dyna S for being impatient.  Once I get it statically timed with the points back in then I will install the Dyna and fine tune it further.

Offline newday777

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Re: Help! Have 12.6 volts from blue and yellow coil wires.
« Reply #2 on: January 10, 2024, 12:58:11 AM »
This is happening before the points were removed.  Now that the points are out I still have this issue.  I do not want to plug in and possibly blow my Dyna S for being impatient.  Once I get it statically timed with the points back in then I will install the Dyna and fine tune it further.
What bike are you working on?(very important to include what it is every time you start a thread)
It seems like you have wired something wrong but without full information from you as to what your working on and pictures of your wiring, you are making us assume (not a good thing!) as to how you have wired this all up.

Reading through your posts, to try to figure out what you are working on, you would probably be better off to start a project thread of this build so you can keep all your information together in one thread. You can post updates and pictures as you go on it and ask questions in it too.
When you start the thread introduce yourself (and your experience/knowledge of bikes) and what the bike build is, how it looked before and you plan of attach and finished plan/direction ideas you have for it.

http://forums.sohc4.net/index.php/board,103.0.html

Just trying to help so you get answers.

BTW are you hitting the notify button so you get an automatic email whenever someone replies to your threads or any threads you are interested in? This forum doesn't do it automatically so you have to manually do it yourself.
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
1983 GL1100A, 1999 GL1500 SE, 1999 GL1500A

Offline Snider1970

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Re: Help! Have 12.6 volts from blue and yellow coil wires.
« Reply #3 on: January 10, 2024, 04:11:54 PM »
 Unfortunately,I  have to reply when I get a chance.  I'm a hospital nurse and we are slammed at this time of year.  As far as the rest I agree that is a good idea. However, I had most of my bike built before I found this page.  I don't have pictures to document my build and seldom use my phone except to play music, look up how-tos, and take quick pic to remember how to put ithings back together.   
The bike is a '78 cb750. 
Drivetrain (motor, carbs, sprockets and chain) are all stock.
I have a m.unit blue to handle the wiring (which works beautifully except this.)
The coils are stock as well.
As far as I can tell from wiring diagrams the ignition with the m.unit is really simple.
You have 12v power from the m.unit to the switch. Check.
You have 12v power from the switch to the coils. Check.
From that point wether the points/Dyna are on or off the bike I believe there should not be power through the blue and yellow wire.
Correct? 
Or maybe the question should be where does the power come from for the points specifically?
I do not know why I can't get my head around this.
Thanks in advance.