Stock Mark III Not Charging?

Got a message from a local MKIII owner that I've helped sort some issues in the past. His bike does not appear to be charging the battery while riding. Its on the original stator/rotor/Rectifier/Zeners/Assimilator. Battery is fresh and he keeps it on a trickle charge between outings. He's a young dude with not much mechanical skill.
I'm not able to be at the bike in person for a while so trying to help him over FB messenger... Suggestions on testing checks/procedures and any tricks on how to access the wiring on the MKIII would be helpful.

Tornado said:

Assimilator

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Is this another Canadian lights on with ignition model?

Tornado said:

any tricks on how to access the wiring on the MKIII would be helpful.

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No "tricks" required as far as I'm aware as another Mk3 owner.

I've had issues in the past that I successfully resolved, not an expert, but I've learned a lot from Greg. Assuming the battery is good, you need to check the regulator/rectifier (DC) and stator (AC) output with a multimeter; you can pick them up cheap on Amazon. I found a number of good Youtube videos on how to do the tests. Pretty simple once you put your mind to it. In the end I replaced the rotor/stator and dumped the old rect/zener/assimilator/capaciter in lieu of a Tri-Spark Rectifier/Regulator and an Improving Motorcycles charging indicator... seemed to simply things. A few hundred dollars but I'm past the problems and have a modern electrical system.

2WheelsUp said:

I've had issues in the past that I successfully resolved, not an expert, but I've learned a lot from Greg. Assuming the battery is good, you need to check the regulator/rectifier (DC) and stator (AC) output with a multimeter; you can pick them up cheap on Amazon. I found a number of good Youtube videos on how to do the tests. Pretty simple once you put your mind to it. In the end I replaced the rotor/stator and dumped the old rect/zener/assimilator/capaciter in lieu of a Tri-Spark Rectifier/Regulator and an Improving Motorcycles charging indicator... seemed to simply things. A few hundred dollars but I'm past the problems and have a modern electrical system.

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Yes, he has a multi-meter but unsure if he knows much about using it ;-) I'm thinking to check the stator output AC and then from the Rec. Workshop says to use a 1 Ohm resistor to test the stator output...but is there a more basic check like looking for open circuit or an Ohm reading range at the GY/GW stator wires? Also, with bike running, is there a range of AC output for the stator wires at 2 or 3k rpm etc?

L.A.B. said:

Is this another Canadian lights on with ignition model?




No "tricks" required as far as I'm aware as another Mk3 owner.

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Yes, likely a Canadian model but it has had work done (by the late/great Dave Sandquist) in its past. He sent me a pic of the rec and it seems well buried between batt and frame etc. Is there an esier place to access the stator wires (GY/GW I think?)?

The original (half wave) rectifier shouldn't be difficult to access although the stator wire connections can be accessed in the normal position where they attach to the harness.

Mine stopped charging on a trip a few years ago.
This was caused by corrosion on the bullet electrical connectors.

Glen

L.A.B. said:

The original (half wave) rectifier shouldn't be difficult to access although the stator wire connections can be accessed in the normal position where they attach to the harness.

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Here's what he sent me....maybe just needs the batt shifting out the way....But I cannot rule out that is a modern Reg/Rec there....

Tornado said:

.But I cannot rule out that is a modern Reg/Rec there....

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Yes, it's not the original 2DV 406 rectifier. If it's a regulator then the twin Zener diodes wouldn't be there or at least not connected either so not on the original parts as you said previously.

That lower side panel pin wouldn't normally be there on a MK3 either.

Tornado said:

Here's what he sent me....maybe just needs the batt shifting out the way....But I cannot rule out that is a modern Reg/Rec there....

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Modern or original, first split the problem in half. Forget what the manual says for now. Find the two (or three) wires that come from the stator. If a regulator is used, they connect to the regulator's yellow wires, if original, they are the two wires that are some combination of Grn/Yel, Wht/Grn, or Grn/Blk that go to the two outside terminals of the rectifier. If two wires, disconnect them. If three, disconnect two of them. With the multimeter on AC volts at whatever range is closest to but higher than 30 volts, connect to the two disconnected wires. Start the bike and rev to around 3000 rpm. You should read more than 15 volts and probably around 30 volts. If you do, you can assume that the stator side it good and the problem is with the bridge/Zeners, or Regulator, or wiring. Before changing parts, check all Brn/Blu wires, including at the fuse and master switch. Brn/Blu takes power form the battery minus to the master switch and also connects to the rectifier or the black wire of the regulator and other places.

L.A.B. said:

Yes, it's not the original 2DV 406 rectifier. If it's a regulator then the twin Zener diodes wouldn't be there or at least not connected either so not on the original parts as you said previously.

That lower side panel pin wouldn't normally be there on a MK3 either.

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Yes zeners are there and appear wired up.

Tornado said:

His bike does not appear to be charging the battery while riding.

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“Does not appear to be!” What does that mean?

First test is: is it charging the battery or not?

Does the voltage at the battery terminals rise to over 13.5 V when you rev up? With lights off? With lights on?

Will the fully charged battery power a 60 W headlight for half an hour, with engine stopped?