ETZ250 Voltage regulator smell & Alternator sparks

[BubbleOz]

Hello esteemed friends,

My 1984 ETZ250, has been working well (electrically at least!) for about 1200 kms. Gel battery, new, voltage at rest 12.59V
Riding the other day, got the red charge light on the tacho. Stopped bike, jiggled the fuse (which fixed the problem in the past), light still on.
Got home. Inspected brushes, 13mm so within spec.
Ran tests using a lamp as per the MZ video Part 6 on youtube (yes I speak German), turns out the right hand side points don't work as they should. Furthermore, there is a distinct burnt smell from the regulator. When testing it sparked a little when moving connections around for testing.

Video suggests if a test fails, get a new regulator. Ordered.

Put all connections back on the old voltage reg, started bike to see if the problem persists. Light does go out now over 2200 rpm; but noticed in the BACK of the alternator, crankside if you will, occasional sparks. Using a mirror viewing the back all appears to be fine, nothing burnt out.

Question: Could the malfunctioning voltage regulator be responsible for the sparks ? Clearly the option of replacing the mechanica voltage regulator that's now 33 years old is preferable to ordering an alternator, which pumps out 14+ V when revving.

Or are these sparks 'normal'?

Anyone had sparks on the back of the alternator?

Thanks for your feedback in advance,

Nik

[Blurredman]

Does the bike charge when both lights are on or off?

Obviously the bike doesn't charge at idle. Two years ago when I was having charging problems (down to a dodgy electronic ignition) I put on a small voltage display. And I never took it off. It's quite handy even now when I know the system is working fine. But allows me to see appropriate voltages in whatever circumstances. 13.5v when lights are on and bike is in motion, 14.5v when lights off and in motion.

Lights on and indicators on at a stop and I get around 10-11 variation (because the indicators are turning on and off). Normal.


I doubt sparks are good behind the alternator. You will obviously see occasional spark from the points though. What are the condition of the points? Perhaps one of the contacts is worn, and instead of arcing to the foot it is finding somewhere else..

Is it possible to do a video?

[BubbleOz]

Thank you, was just out trying to get a better understanding...so got a video too.
Bike does charge over 2500. After a ride around block volts at rest with engine off is 12.89, > 12.53 that it was before I rode.
Taking the video....the noise makes me think bearings are on their way? Or the reg fried?
I used to change these on car alternators, the noise with the spark might be telling the story..
Link here https://youtu.be/Xn1Xzn1Fdjs

Thanks muchly,
Nik
PS: could I commute like this?

[Blurredman]

I'm not sure, but it sounds like there is air induction noise? Does the bike normally sound like that? It could be the main seal/and/or bearing has gone?

I wouldn't ride it myself, it sounds conducive to a probable failure whilst riding. It sounds quite poorly, actually.


Take the stator and rotor off and look for splits in the seal, also see if you can find any play in the crank?

[BubbleOz]

Well she rides very well, but frankly never ridden it without a side cover so impossible to say.
As for bearing , engine was rebuilt about 1200k ago and once carburettor was sorted she rides fine...

The noise is weird, but might be an alternator bearing..the quest continues!

Thanks very much,
Nik

[Blurredman]

There's no actual bearing on the rotor. It's tapered on just like the clutch.

I hope somone else will come in with a possible thing to look at - as helpful as I am trying to be, I'm not master I only re-built the lower end of an MZ engine a couple of months ago after 6 years of owning one.

I'm wondering if the engine is properly earthed? Some people put a wire from the engine rear mount and lead that to a more decisive earthing point on the frame. I intend to do this myself actually at some point. Though I have no problems (I think)- with a 12v system there is quite a leniency for bad connections that you would notice more readily with a 6v system.

I've ridden my MZ's without the side cover on semi-frequently when I get a problem with points or when adjusting points, and I've never seen sparks from behind the stator before.

[BubbleOz]

Well upon closer inspection, can see the tiniest metal shavings..which would have explain the sparks.

Yes you're right, no bearing, just tapered on.

[Blurredman]

I wonder where those shavings are from. Perhaps the rotor is not true on the crank end? I would inspect the stator for wear marks from possible scoring of the rotor. I wonder if it's touching or perhaps even the stator is not on square?

[BubbleOz]

It is possible - I had a lowlife knocked the bike off the centre stand on its left side, so it's possible something is off kilter..
Keep you posted

[BubbleOz]

A picture is worth a thousand words...
Best cancel the replacement regulator I guess...

[Blurredman]

I suppose that is the C Clip that retains the seal?

[BubbleOz]

Sure is. .packs a mean spark
Put everything together, but not started her, but am quietly confident

Cheers,
I'll go find a rock and hide under

[BubbleOz]

And after fitting it and using the woodruff key to line it all up.... kicking feels funny. Seems I lost the woodruff key! Now I need to find the little bugger...

[Blurredman]

Oh dear !