MZ ES 250/1 electrical , spark plug, ignition and charging

[grimstone]

Hello,
My bike, am ES250/1 1962 was neglected for a long time by me and finally now we got reunited and I start the restoration.
One of the questions I have now is about spark plug.

Initially , 15 years ago someone put a long sleeve spark plug inside which did not fir to the factory specs. It also looks very burnt.
Look at the pic:

One of the mates here observed that the plug is too long so I took head off and here is how it stays in the combustion chamber:

This is how the recommended ngk b8hs stays:

and this is what I found that a plug should stay:

https://www.cyclepedia.com/manuals/onli ... 235413.jpg

So neither plugs stay in the correct location???? I have 2 heads, in both of them the plug reach is the same.
Beru ZM14-260 isolator spetzial has a reach of 12,5 mm and ngk B8hs has a reach of 12,7 mm.

Anyone with any experience on this subject?

Can someoane measure a head and tell me the lenght of the thread, maibe both of mine have been altered. No mine have 15mm thread lenght.

With the recommended plug the engine seems less noise and more "round" running.
The specs of the Beru Isolator ZM14-260 are the same in terms of dimensions as the NGK B8HS.
I will put and auto oscilloscope on the bike and see how the primary wave and the secondary burn wave look with both plugs installed and will post.
Until than any advice is very welcomed.

[mr_luke]

Can you post a photo of the cylinder head from the outside, without a spark plug fitted? I wonder if the thread has been repaired with an insert at some point in the past?

[grimstone]

so the ngk and the long plug stays the same in both. here is a pic on the es250/1 head:

and from the es175/1:

They both seem sleeved/repaired but I cannot imagime how someoane would repair and not be consistent with the original lenght.

Someoanechas a pic with a stock head?

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[grimstone]

Can you measure with a caliper the thread inside tge head?

[grimstone]

Hello,
Here is the data from the primary and secondary ignition with b8hs.
The burn is definitively very rich:

Below the data. first line from bottom is the primary ignition, meaning how the coil performs and the second line is the actual burn inside the cylinder. Will have to analyze and see but besides being rich ...

Ignore the measurements, they are compensated by some atenuators.

[grimstone]

I am also reading a lot on using isciloscope for automitive diagnostics so here is some documentation on secondary ignition waveform interpretation

https://www.picoauto.com/library/traini ... -ignition1

[grimstone]

Holo first issues I detect on my burn quality. See below:

numbers from the pic commented

1. (circled in the pic) pri looks good, this is the moment when the circuit is switched on ( ign coil is connected). but the secondary should be the same following a almost 0 volt until discharge and it does not, this means a poor connection to ground somewhere.

2. this is serious. the line from sec that corespond to the pri on the second spark event is good but on the first it does not even exist meaning that there was not sufficient energy from the coil to start the spark. This is maibe of the bad ground.

So on the tools now to solve and find the bad ground. Bike is acting weid like when I switch on the headlight the engine stops and this is with no light bulb connected....

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[grimstone]

1. Thx

2. 32:1 i use as per manual. I will try reducing it but I do not want to risk over wear in the parts.

3. It is burn quality in fact more coectly said is how the spark energy evolves between the 2 electrodes inside the combustion chamber. I read that with a probe on the HT wire. And analizing how that energy evolves tells a lot on burn quality, quality of mix, etc... In 4T engines i usually detect like this silt on the exgaust or intake valves, compression issues, atomizing quality of injectors etc... I am still learning with every engine I analize but... If you are interested I can send you a wave from my F650gs BMW witch gas a issue with idle control actuator or the injector. In that the seconday wave and especially how the spark develops is far more bad than the MZ.

4. Yes it has park setting but that is oppozite to the off position. Even with the position lights only selected I have engine stopping and that one has a bulb connected and the bulb lights. I will have to close check everything on the electrical system or buy an entire new cable harness since the one on the bike was patched and abused many times by previous owners and is not even original. For exampke connections to signalling is done with a piece of 3P wire cut from a household electrical extender ... I will also have the entire switch checked.

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[grimstone]

I have no washer there so i assume that the repair was not done correctly and the bush is higher that needed. I will have to repair that.

Silt... i ment carbon deposits .. sorry.

i have an es250/1 so it is 1:33. I may go 1:28... but do not want to risk. I will sort other issues and at the end I will concentrate on this fine adjustments.

Maibe I am not explaining things very clearly and certanly I am not. Look here:
https://www.autosuccessonline.com/scopi ... ave-forms/
Compression: i do not measure exact compression I usually get a relative compression and I measure , without starting the engine, how much amperage is taken by the started motor to be able to rotate the engine. If a cylinder has less compression the amperage would be lower. Of cours efor real compression I put a senzor in the spark plug hole and rotate the engine. I know the values that the sensor sends so I can convert to PSI/BAR .
Electrical really needs to be rewied on the bike. I m in the process right now, and rteally scratching my brains since all wires on the bike are either black or red...

[Puffs]

Following a biased and flawed moderator choice (someone posting aggressive personal attacks is rewarded, while my technical posts are removed - behind my back & without any justification!), I have withdrawn from this forum.

[grimstone]

Thx.
What I am looking for in the secondary ignition waveform on my bike is the dwell time and form and the variations between 2-3 sparks of the firing voltage line. If you see in most "perfect" curves that dwell line increaseas slowly and after that comes the discharge. On mine it increases very steeply and from what I read this can be of a tired capacitor, points gap beeing too big, a imperfect ground contact or even a tired ign coil. I will have to test each of them, most eSi now beeing the points gap. As for the spark line sometimes is inexistant and sometimes is very high and sometimes very low. This tells me that the ign coil does not charge the same every time and is not able to deliver same spark voltage. This might be case of too large points gap, tired capacitor, tired ign coil or improper ground.. So I need to review these and see if I get better results with a smoother running engine. In fact that is all I whant: proper and smooth running engine to prevent premature wear of components. And of course I might have a passion for these things )))) You should see how the secondary waveform looks on my 2001 f650gs bmw which is fuel injected. Perfect until the spak line, after that dissaster. The MZ looks way better )

Today I repaired some connections at alternator side and the engine is not stopping anymore when I switch lights on and I started to see 7,8 volts at battety terminals when adding some throttle, previously no more than 6,4. Keep in mind yhat I am running with electronic charging comtroller ( still have the old mech one as museum part or until I learn how to adjust properly).