TOPIC:

Grab your meter

Rotate engine with a wrench till both of your points are closed
meter on DC V
bike ignition on/engine not running.

Red meter probe on positive battery post( the post will be the metal part of the battery that the cable attaches to)
Black meter probe on negative battery post
Note voltage

Move your red meter probe to the ignition coils' positive terminals.
Note voltages
Move red probe to each of the coils' negative terminals
Note voltages

While you're there, rotate the engine till one of the points open up.
Black meter probe on negative battery post.
Red meter probe on each of the positive coil terminals
Note voltages

move red meter probe to each of the coils' negative terminals
Note voltages

Rotate the engine till the other points open
same measurements

Black probe-negative battery post
Red probe-positive coil terminals
Note voltages
move red probe to negative coil terminals
Note voltages

Shut off the ignition as the coils may overheat if left on too long.

F64 - Thanks for the instructions, I will check it out tonight and report back.

Just a comment, rotate engine with the 17mm nut at the advancer.

Here's what I found last night -

battery voltage w/ignition off - 12.36v, w/ignition on - 11.96V
both points closed - positive terminals - 9.38V, 9.38V, negative terminals - 0.43V, 0.78V
one point open - positive terminals - 9.33V, 0 V negative terminals 0.767V-1.4V, 0 V (note voltage was rising on one terminal like there was a capacitor charging up)

I also check the ignition coil resistance, they were 4.7 ohms and 5.0 ohms. The one that was 5.0 seemed to be bouncing around more than the other one and is out of spec slightly (should be 3.2-4.8). These appear to be original coils and the rubber boots are pretty cracked and dry rotted.

magilla wrote: Here's what I found last night -

battery voltage w/ignition off - 12.36v, w/ignition on - 11.96V
both points closed - positive terminals - 9.38V, 9.38V, negative terminals - 0.43V, 0.78V
one point open - positive terminals - 9.33V, 0 Vthis looks like a loose connection. it should 9.38 volts. You had 9.38 volts on the "points closed" test above so something may have come loose. negative terminals 0.767V-1.4V, 0 V (note voltage was rising on one terminal like there was a capacitor charging up)

You have a huge voltage drop on power going to the coils

I also check the ignition coil resistance, they were 4.7 ohms and 5.0 ohms. The one that was 5.0 seemed to be bouncing around more than the other one and is out of spec slightly (should be 3.2-4.8). These appear to be original coils and the rubber boots are pretty cracked and dry rotted.

There's a bad connection hampering you.
That is probably contributing is your low voltage at the coils.
9.33V is really low for coils.



Grab the meter
DC V
ignition on/engine off
both points closed
let's do this in 10 minute spurts as your coils may overheat. (i did a quick search on how long it takes to overheat a coil..I couldn't find anything specific.)
let the coils rest for 5 minutes

Black meter probe on negative battery post
Red meter probe on positive battery post
Note voltage

Red meter probe will now probe the wires in the colored boxes from the coils back to the battery. Any time you have a large jump in voltage, that is an area where there is a problem. It could be corrosion, high resistance, bad connectors.
ok
red meter probe on the connector in the red box (red/yellow wires from coil----read both sides of the connector)
Note voltage
red meter probe on pink box connector(brown wire coming off of kill switch on right handlebar--may be in headlight housing---read both sides of connector)
Note voltage
red meter probe on blue box (looks like a gray or white wire coming from ignition switch. read both sides of connector)
Note voltage
red meter probe on the pink circle( same white wire single connector-read both sides of connector)
Note voltage
Red meter probe on black box(measure both sides of 20 amp fuse)
Note voltage
Red meter probe on teal box( measure both sides of connector)
Note voltage
Red meter probe on Battery cable terminal at battery(not the battery post---you're checking if you have corrosion on your battery terminal)

Red meter probe on positive battery post
Black meter probe on negative battery post
Note voltage

Black meter probe on negative battery cable terminal
Note voltage
Black meter probe on your points plate(you can touch anywhere on the plate)
Note voltage

turn off bike ignition

I started checking voltages last night. I started at the fuse box under the left side cover and found they were all low voltage, around 9.6V and were all three getting very hot, so hot I could not touch them, but none of them blew. I also checked the voltage at the engine kill switch and it was 9.6 volts on both sides of the switch. I disconnected both hot leads to the coils to see if that made any difference and it did not. Since the fuses were getting so hot, I stopped there. I thought there must be a short somewhere. I talked to an old mechanic in my office this morning and he suggested checking the ground since nothing after the battery is showing 12 volts. I will try that tonight.

What is interesting...is that you were sooo close to finding the issue.
It may be your battery terminals.
If you have corrosion on them, the voltage drop will be there. That's why I have you put the meter probes on the battery posts...not the battery cable terminals

When you have a chance.

Bike ignition on
meter on DC V
On these next group of measurements, anything over .5 volts dc is bad and is a sign of high resistance

Black meter probe on positive battery Post
Red meter probe on positive battery cable Terminal
Note voltage

Black meter probe on positive battery post
Red meter probe on the connector in the teal box(white wire)measure both sides of the connector
Note voltage

Black meter probe on positive battery post
Red meter probe on the fuse in the black box
Note voltage

Those readings will cover the positive circuit completely.

Now the ground circuit

Black meter probe on negative battery Post
Red meter probe on negative battery cable Terminal
Note voltage

Black meter probe on negative battery post
Red meter probe on frame ground mounting point(follow ground cable from battery to frame mounting point)
Note voltage

Also, check the value of that fuse you were metering. There is a possibility that the fuse rating isn't what is supposed to be in there. The fuses protect the Wire. Not the loads.
If the fuse values are higher than they should be---fire...the wire will melt anything in it's path. I know this--I set my first car on fire. You learn pretty fast what fuses are for.
It looks like a 20 amp fuse on the schematic.
Check your other fuse values as well.

Luckily I haven’t experienced this but most times low voltage is discussed it seams to lead to a bad connection in either the ignition or at the fuse box... but the first place is the obvious locations that are less intrusive.

True, but if was at the ignition switch...the wire going into the switch would be 12v. The wire going out would be 9V.
If it were the fuse box, then the voltage going into the box from the battery would be 12v and going out would be 9v.
Magilla has eliminated everything on the positive circuit from the fuse block out. He just needs to check from the fuse block back to the battery and the ground side.
All of this testing has to be done with the circuits loaded(bike ignition on) Otherwise, it would appear everything is 12v on the positive side.

With the tank and headlight removed it takes about 20 minutes to unplug and clean all the connectors. You'll need to do that at some point anyway.

Most of his connectors are fine. The issue with connectors sometimes is that they are rated for a certain amount of unplugging and re-plugging.
After that, you have to replace the connectors. It's easier just to probe with the meter and look at the entire circuit.
It also could be a pinched wire or corrosion within the wire--cleaning a connector would not fix either of those faults.

Photo: www.kmpdrivetrain.com/general/practical-...rt-wiring-harnesses/