ETZ251 Charging System.......

[difflock]

Right.

The other day, I fitted the generator seal clip that was missing, and upon fitting it, the bike started and ran beautifully....

I went for a ride, and it pulled the best it EVER has....
I was happy
it would pull happily from 2,000rpm to 6,000rpm and accelerate hard once in the powerband (once the engine was warm)


then about 3 miles into the ride, the charge warning light came on...
now to keep the engine running, I had to keep the revs above 3,000rpm or it would try and stall
which meant (on the lanes home) I was in first and second all the way.

now I did rev it a bit out of one of the corners (5,500~6,000rpm) and the red light dimmed down/turned off

but it only happened once or twice...


the bike still ran fairly well as long as the revs were kept high.



I managed to get home, and I removed the seat, and checked the charging system.
the (mechanical) regulator tested OK, I havent checked the rectifier yet.
the battery had a good amount of charge (and its fairly new)

but now the bike wont start.....

its got a good healthy spark, its getting fuel into the cylinder, and its got good compression
its spluttered a couple of times, but nothing more....

its currently running premix (50:1)


any ideas?

[DAVID THOMPSON]

is there a float bowl drain in the carb
every time i go on reserve side of tank
my rt125 will not run
takes a couple bowl drainings to get it to go again
need to get a sediment bowl on mine
the car filter does not get the junk out
dave

[difflock]

the carb has been apart several times and theres never any sediment in it.

the PO cleaned the tank out....




I definitely think its something on the charging system......

[difflock]

Right, its still being a pain.
it will sometimes start and run, but its selective at best....

now I havent taken it for another ride, as I dont want to be stranded.....



so, any ideas?

the charge light came on when I was slowing down, and then wouldnt go out.
it wouldnt run properly then below 3,000rpm, and would try and stall if you were below that.
above 3,000rpm it ran almost as good as before the problem.

the points are adjusted properly, its got a new condensor, and the battery was at ~12.7 volts (so not flat)
its got a good spark, and with the ignition off, it wets the plug.
the carb is nice and clean.

I've checked the points are opening/closing properly, by testing the voltage at the coil.




now the way it came on suddenly, and wouldnt run properly at lower rpm, to me points that the generator was having to power the plug completely (and not relying on the battery at all)
so that would point to the charging circuit, wouldnt it.....

So, any ideas what to test/bypass/replace?



I've got a CB500 reg/reg unit that I can use if needed.
its got 5 terminals on it.
3 for the stator (which are wired in the same on either the CB500 or MZ)
then its got 2 more connections.
one is earth, and the other goes to the positive of the battery.


I'm thinking about trying it and seeing if it makes a difference......

[difflock]

Slight update....

I managed to get it to start again after writing the last post....


It seems the regulator tests OK (terminal to terminal, and the gaps internally), but its over charging.

I put my voltage tester (on the 20v setting), on the terminals, and expected to see 12~14.5 volts....
it was reading between 17~19v at ~2,000rpm.
when the engine revved up a little, it exceeded 20v!

not sure why that would make it hard to start though :S



any thoughts?

[DAVID THOMPSON]

need to get that reg unit checked before you toast the battery if you have not already
and you may find other things gone like lamps and it can kill the coil doing that
dave

ps check that it has the correct bulb in the charge indicator
on some bikes with generators that needs to be the oem bulb
or charge rate can be wrong

[difflock]

I'm hoping the battery has survived

I'm not going to run it, until the regulator is replaced with a working one.
I dont want to kill anything....

I'm still wondering if I can fit the CB500 regulator....

[Old Dog]

MZ-b do a solid state reg/rec or indeed a complete system which is brilliant!!

[DAVID THOMPSON]

see this link for electrical
things changed a while back
and the electrical is a new web site
dave

viewtopic.php?f=18&t=3811

http://www.powerdynamo.biz/eng/sitemap.htm

http://www.powerdynamo.biz/eng/systems/ ... erview.php

[Skorpion]

If your regulator-rectifier is the mechanical type, and your CB500 unit doesn't work, I found this on ebay.


http://www.ebay.co.uk/itm/MZ-ETZ-125-25 ... 415915d0db

[difflock]

Yes, I've seen the MZ-B/Powerdynamo kits....

they are very nice but a lot of money

I was hoping I could fix the MZ for as little as possible (preferably free)

I might have found somewhere that sells the Lucas NCB403 regulator for ~£15 though....