Coil circuit question

[pdqford]

Okay guys, I found my notes from when I cleaned up the electrics a few years ago (and haven’t even ridden it since!)

Back then I was using my ohm meter and broke the coil circuit down into three segments.
Segment A was from the positive battery cable (disconnected from power) to the main glass fuse: 0.2 ohm.
Segment B from main fuse up through ignition switch and back to the ignition fuse: 0.5 ohm.
Segment C from ignition fuse up through kill switch to coil connector: 0.3 ohms.
For a total of 1.0 ohms.

Went out there now and from the positive battery cable with ignition switch turned on all the way to the coil connector it is reading 1.9 ohms! Looks like I have to do the cleaning all over again. I had used DeOxit but I didn’ Use any dielectric grease.

And I found my notes from firing it up with before and after cleaning (prior to doing the carbs and valves) :
Before: @2500 rpm battery voltage was 13.3 volts and voltage at coil was 10.8 volts! (About where I am now!)
After: @2500 rpm battery voltage was 14.3 volts and voltage at the coil was 13.7 volts!
(I could actually HEAR how much better it ran!)

So I guess I get to start all over.

(Still don’t know why turning on the headlight effects my coil voltage but not the battery voltage, but that will be a problem for another day.)

Thanks again everyone.

[posplayr]

Okay guys, I found my notes from when I cleaned up the electrics a few years ago (and haven’t even ridden it since!)

Back then I was using my ohm meter and broke the coil circuit down into three segments.
Segment A was from the positive battery cable (disconnected from power) to the main glass fuse: 0.2 ohm.
Segment B from main fuse up through ignition switch and back to the ignition fuse: 0.5 ohm.
Segment C from ignition fuse up through kill switch to coil connector: 0.3 ohms.
For a total of 1.0 ohms.

Went out there now and from the positive battery cable with ignition switch turned on all the way to the coil connector it is reading 1.9 ohms! Looks like I have to do the cleaning all over again. I had used DeOxit but I didn’ Use any dielectric grease.

And I found my notes from firing it up with before and after cleaning (prior to doing the carbs and valves) :
Before: @2500 rpm battery voltage was 13.3 volts and voltage at coil was 10.8 volts! (About where I am now!)
After: @2500 rpm battery voltage was 14.3 volts and voltage at the coil was 13.7 volts!
(I could actually HEAR how much better it ran!)

So I guess I get to start all over.

(Still don’t know why turning on the headlight effects my coil voltage but not the battery voltage, but that will be a problem for another day.)

Thanks again everyone.

1.0 ohm (upstream of the coils) and an average 2.5 amp load from the coils is a 2.5 volt drop to the coils. 13.3-2.5=10.8V just about what you measured.

I usually don't recommend using an ohm meter because you are adding up 0.1's of an ohm and there can be significant errors just in the probes. The meter is best for measuring resistances well above 1 ohm.
It is much more accurate to just turn on your loads and move from battery to the load and then back measuring all voltages.
You can adjust voltages based on any battery voltage sag you might have had.

[pdqford]

Okay. I made good progress today. Pulled the glass fuses and cleaned them up with DeOxit as well as the fuse holder clips and added a thin coat of dielectric grease to all contact points
Took the kill switch apart and sprayed it down with DeOxit. Pulled the ignition switch and did Ditto. Also, same for the connectors in the O/W wire circuit. Put the ohm meter on the entire circuit from battery positive cable to the harness side at the coil connection. Presto/whamo, the over all circuit resistance went from 1.9 ohms down to 0.6 ohms!!!

[pdqford]

Next, I tested the battery condiction before connecting up the cables, to see if I had pulled it down too much from my testing.

[posplayr]

I did not realize you were using the old glass fuses. You need to open your fusebox up and clean those crimps as shown in the picture below. I use naval jelly, set 15min and flush with water.
Then using some liquid flux, flow a small amount of solder into the crimps.
Finish off with the Deoxit.

https://www.thegsresources.com/_forum/attachment.php?attachmentid=25103&d=1239471120

[pdqford]

Then I hooked the cables up to the battery, had the big meter hooked across the battery and the small auxiliary volt meter hooked up to the coil connector, turn the ignition key to “on”, and

[pdqford]

So, hopefully, tomorrow maybe I can get a temp fuel supply hooked up and verify that my carb sync hasn’t gone away since we synced them last fall.