MZ/MuZ Riders

Hi guys.

Find my Trusty mz 251 is not charging.
I manage to have time to have a look to-day to find that the W terminal on the generator side is melting wire/connector- It had one of those crimp type put on by the previous owner- and the sheeth has melted too.

Wehether this is just a symptom or a cause of my charging issues- Not sure. Perhaps the connection became resistent and because of that it got hot I take it?

Will be putting new connector on tonight, and cleaning up male spade on the generator as it is now corroded, and seeing what happens.

The core of the wire itself looks a bit fluffy and probably won't take to solder very well so may run a new wire.

new wire with real copper in it is best and spades soldered on wire
i remove the plastic cover on the spades and solder the wires on

the harness in my 2002 rt125 is getting tired and its just a young pup

DAVE

Indeed David, the problem with old wiring is that over time the copper can degrade. I have this problem big time on my Honda, and on my Buick. I do luckily have lots of wire that i've collected over the years, indeed some of it is MZ loom so I can directly replace without having to even put connectors on.


Anyway. Bit of an update. I put in a fresh wire. The bike charges.

It does however, only start charging at a higher RPM than it did before. The idle is higher than it was before (similar to what the bike would typically do when a phase wire is no longer connected), and the 'charge light' is on very dimly up until around 3k, despite the charge kicking in around 2k rpm. I would also like to add that I have slightly smaller gauge of wire, but not too un-parallel to what was originally there.

I'm not worrying about it too much at the minute, as it is charging and at a not un-reasonable kick-in point, the regulator is also doing it's job- But I have the feeling the rectifier may have been affected. I do have a spare, but it wasn't with me tonight in order to test it. Watch this space. I will also have to test the resting voltage of the battery after a night sitting- as this battery has run down a few times now.

always try to get the correct lamp for the charge light in some systems the wrong one can cause
problems as it is used as a limiter sometimes

dave

12v 2watt. The charge lamp is not the problem here


UPDATE- I think the stator has been shorted. With the lights off there is a charge, although higher than usual. With the lights on, the voltage display does not identify a voltage output above 13v until about 3k rpm. That's not really ideal.


I have a spare stator unit, but it is also broken, Howwever, I am unsure whether it doesn't charge when the lights are on or off, it's one or the other. I will fit it and find out- if it only charges when the lights are off (on my spare) then it's a little useless and i'm back to square one where I will have to purchase another anyway.

Update guys:


I went to my lockup where my other MZ is and did the following:

Changed stator- still no work
Changed rectifier - still no work
Changed regulator (again- this time for a mechanical one) - still same issue.

Decided that the only other thing that may cause it is the electronic ignition. And decided to pack up and go home. On the way I popped into Tesco's..
I came back to the bike and it wouldn't start- No spark! I guess the electronic ignition unit is gone... after 12,000 miles Was not a nice push home- (i've lost my spares pouch that contained spare points etc)

No spark means an ignition problem, but I don't quite see how your ignition could cause charging problems. You had a system wherein a Hall sensor replaces the conventional contact breaker points, right? Maybe it shorted somewhere, or closed for too long (coil hot?). Back to the points & you'll know (if you still have any...).

Puffs wrote:No spark means an ignition problem, but I don't quite see how your ignition could cause charging problems. You had a system wherein a Hall sensor replaces the conventional contact breaker points, right? Maybe it shorted somewhere, or closed for too long (coil hot?). Back to the points & you'll know (if you still have any...).

Exactly. I wasn't sure how it would affect the charge point. But then, maybe a voltage spike or possibly a hot wire lead to the electronic system?

Either way.. At some point soon I will fit a points system back on- at least to get it movable for small distances, as the reason I put electronic on it was because it was oddly impossible to set the correct spark plug gap. Regardless of how many contact breakers, stators, lobs, I used...

Annoyingly the pouch I used to carry with me everywhere has gone missing- So my spare parts (ie the above mentioned points and lobe) have disapeared! So I can't immedately test this.


Yes. It is a hall effect unit. This unit also apparently had a built in feature which dropped voltage to the coil if ignition was on but the sensor wasn't passed through within 10 seconds. Once the sensor does pass through voltage is admitted to the coil again.

***UPDATE***

Interesting development, but I fear no one is really reading these.


I have taken the electronic ignition off the machine in question and I have re-instated the contact breakers. The bike now starts and runs!!


BUT-

The same issue as I have stated in my original post. The charge light is on dimmly at under 3k RPM.. What could this be I wonder.. I have changed the Stator, changed the regulator and changed the rectifier.. But this issue of not charging under 3> rpm, and especially that be anywhere near 13v until 4k with the lights on... I must add that I have also changed the pickup brushes, numerous times..

I really am a little bit stumped now! :O The only thing which I think I can really do, is change the W terminal wire for a larger gauge, but I can't really see that doing much of a difference..!! I am a little bit worried, that the replacement parts I put on the bike are now also defective !??

I have the same feeling sometimes - yet I do read your posts.

But I can't advise you on the charging issue...

people are reading but very few understand electric theory that = no answers

and then there is Murphy i have a weed eater gas trimmer it will not run on brand new spark plugs the maker says to use

but will run fine on the recommended NGK plug or almost any thing you stick in it but the recommended brand

DAVE

If all the parts are OK it must be a connection or a cable issue. But you know that & saying it doesn't help - the problem is finding the fault.

Maybe cleaning the regulator points and resetting the voltage might help. I had something similar happen about 40 years ago (on a Yamaha). The regulator points stuck and pumped up the voltage so high the headlight blew and some wiring melted. After cleaning the points and resetting the voltage everything was OK.

Thanks for the input guys.


I must state that the type of regulator I have used to test have been a mix of solid state and mechanical. I have tried another solid state one, and a mechanical one. The bike had a solid state one on it until this issue.

I also have a voltage display. I have never noticed any overcharging. Infact it was very good, as it happens. But.. I will replace the wiring loom completely. I will also try a different battery. As there really isn't much more I can try, as Puffs has said.

Well I feel like a complete idiot!


The original problem has been solved.


To help me identify which of the three wires from the rectifier goes to each terminal of the stator, I wrote on each connector U, V and W.

The W wire was the one which burnt, so naturally I put a new wire in place there. But It seems I had the W and U mis-identified each end so therefore there was still a winding not providing any current to the rectifier. With the help of a multimeter I find that the U terminal was identified as W on the other end of the wire- I re-instated the wire the other way around and it is now working.



Next quest: Electronic ignition- Why my current item is broken- And whether it can be fixed. under-voltage wouldn't have damaged it.