MZ/MuZ Riders

Hello there.
Earlier this year I was gifted a very sorry looking TS125 Alpine.
My first MZ, but the more I look into it, the more I appreciate the design and its simplicity.
A few months on and I have rebuilt the engine and had it running but am suffering from a dragging clutch and poor idle.
However the problem I least understand, is the electrics.
I have put a multimeter on the battery to look at the current direction and can never get any positive charge.
I also note that the mechanical regulator isn't doing any switching as I rev the bike.
Specifically - I notice that when I turn the ignition on (before I start the bike) there is 3 Amps draining from the battery. This seems high when there is nothing much switched on.
Can anyone comment on this?
If the battery is draining what is the best way to find the source?
I have found a very useful document here (thank you to whoever wrote it).
https://pic.mz-forum.com/lothar/Elektrik-en/MZ-Elektrik.htm And have been following the steps but don't really understand the results.
Anyway - thanks for accepting me on the forum, and thanks in advance for any help.
Steve.

make sure that when key is on only coil and brake lamp are working and dash lamp
some of the brake lamps the wire grounds in the brake drum and some times when its not supposed to
it works and runs down your battery\
a dash lamp is fused and also the stop and tail no dash lamp no stop and tail power
equals you just got hit in the a$$ the dash lamp out means no power to tail its a safety thing

These are helpful replies - many thanks.
I can confirm the brake light is not stuck on - but I didn't realise the dash light indicated a rear light fault. That's actually pretty clever.

Puffs was right about the coil's primary.
If you open the points the current drops to almost nothing. So that explains the 3Amps.

I have run some continuity checks on the windings of the rotor and have the same resistance between each pole.
I think this is OK.
Perhaps there is something on the field windings which is not right?
The generator housing is actually from another bike because this engine was partly full of water and the generator had corroded beyond repair.
I'll see if I can make some measurements here.

Thanks for the manual link - I'll download it at home so I've got it on my home PC.
Cheers.

I have now run quite a few resistance checks on the rotor windings and the field coils and cannot find anything wrong.
I am now wondering if the generator output is OK and the problem is the mechanical regulator?
Is there a way of measuring the dynamo output.
Can I measure a voltage or current up at the regulator to check there are some electrons there?
Sorry for all the questions.
I am a mechanical engineer and feel like an electrical idiot.

check this out for mechanical
it will make you humble
as will a teletype corperation keyboard and printer KSR 28

https://www.vcalc.net/cu.htm

Wow! What a machine!
Only... Wasn't the slide rule also mechanical?

the curta is a whole different thing the fellows that know how to use one cry when there s breaks

I'm sure.
I should have a few slide rules somewhere. No batteries, no bulbs, I'm sure they'll still work. No use either... Somehow I find this laptop more effective.

But still - being able to capture the complexity of calculus in a mechanical device like the Curta is most admirable!

Thanks for the continued help.
I managed some checks from Lothar's extensive document (very grateful).

I wanted to establish if the dynamo had an output so that I could then turn my focus to the regulator, if this was the case.
Following this procedure

I got the required output of 12V with the bike revs increased.
So I think the generator is working.
I heed Puff's comments about the current needed for the field coils, I may check that again, but I think the output is correct.
I need to look at the regulator next, but I might try swapping in a solid state one, I don't know what the opinion on this idea is?

The other issue I haven't asked about yet is the clutch which is dragging quite badly.
I've made all the necessary adjustments - I even tried eliminating the free travel to maximise the clutch throw, but of course won't ride it like this, it was just to prove a point.
Even in this setting I can't select first gear without the bike either stalling or moving off.
Can I ask if anyone knows what the clutch throw should be?

I measured 1.2mm of movement at the back of the clutch actuator. Does that sound enough?

Many thanks.

a friend of mine once said that the bulb that indicates charge in some systems
can cause problems if its not the factory OEM item ???

used to fix electric on a guys t120 triumph its biggest
problem was HIM he would not keep his hands out of it when it was fixed

it was so bad the other riders said if he kept working on it
when i had it fixed they would ban me fixing it

stevebod wrote:Thanks for the continued help.

The other issue I haven't asked about yet is the clutch which is dragging quite badly.
I've made all the necessary adjustments - I even tried eliminating the free travel to maximise the clutch throw, but of course won't ride it like this, it was just to prove a point.
Even in this setting I can't select first gear without the bike either stalling or moving off.
Can I ask if anyone knows what the clutch throw should be?

I measured 1.2mm of movement at the back of the clutch actuator. Does that sound enough?

Going through exactly the same issue on mine at the moment. Clutch throw is around the figure you quote. Clutch basket, centre splines and driver/driven plate tongues are all perfect! First is difficult to select when cold, the bike stalls with the clutch out without a good handful of throttle.
I've found the condition improves vastly once the clutch is hot, to the point I get only a tiny rev. drop.
I suspect the oil maybe the culprit here. I'm using the manual-specified 80-90 EP oil, but was thinking of trying non-EP, or lowering the grade. Will let you know when I get around to it (have kickstart ratchet issues to sort first).
I'm getting VERY good at stripping the clutch!!

Hi,

Are you trying to find a problem where there may not be? In relation to the amp draw? I can see you have an amp gauge on your side box. But ultimately, when the bike is running is the amp in the positive range? I know you may not be going far with your clutch in the prediciment that it is, but is there a problem with the bike whilst riding in relation to the electrics?

Just curious

Welcome!

Thanks for the useful comments.

@Throwley - I'll be interested to hear the results of your oil experiments.
I think the oil is wrong in my gearbox, so could be causing a drag issue, but I haven't got it running well enough to try it when warm.
Like you, I can't see anything wrong with the plates or the basket or the actuator mechanism.

@Blurredman - you could be right. This is my first MZ and was a non-runner when I got it.
So my logical approach was to get it running and then check it over. That's when I noticed no current going into the battery and no activity from the regulator.
Once I get the clutch sorted, perhaps some road test are in order to better understand if there is a problem.

In the meantime I have ordered an electronic regulator which will at least give me something to swap in/out for comparison tests.
I hope it comes with instructions though and I am reading that sme of them do away with the adjustable resistor for the field windings.
Cheers.