MZ/MuZ Riders

Hello everyone,

My name is Jakub and I am from Poland. I graduated University of Technology and this topic is about my master thesis I made it 4 years ago as a laboratory station and some time ago implemented it in a motorbike MZ ETZ 250.I would like to present my own electronic ignition unit with programmable map. Let me know if you are interested in such device. I will answer your questions with pleasure.


Ignition cut off at 6500 rpm (do not suggest the value on tachometer):
https://www.youtube.com/watch?v=ewkm1O29rOw

How it looks without cover:
https://www.youtube.com/watch?v=3SpDF1CzT08

regards

Hi Jakub!

Yes, a programmable pre-ignition is interesting: many processes occurring in an engine are more or less constant in time, although they are timed (or triggered) against crankshaft orientation. Examples of such processes are: the progress of the flame front after ignition; or the flow of gasses more generally, such as through the carb or exhaust. As those processes are timed against crankshaft orientation, at higher RPM there is less time for them (at 60RPM a full rotation takes 1.00s, at 6000RPM just 0.01s). Consequently triggering them at a different orientation (often earlier at higher RPM) can be beneficial to the performance of the engine. Examples are: ignition timing, exhaust timing (in 2 strokes with an RPM-dependent exhaust valve), but also a reed valve (on a 2T) works largely by influencing the timing of the inlet.

Your 2 videos do not teach me much: one shows a nice ETZ250 that runs well, but seems to start to run a bit mangy around 5500RPM; and the other shows some electrickery, and something rotating where normally the breaker cam is.

The graph you show is quite interesting, and on that I have some questions:
1) I do not see a clear cut-out above 6500RPM. I would have expected to see a step change in ignition timing (to something like 0° or -20°) at 6500RPM, but what I see is just a continued trailing-off of the advance.
2) Your ignition advance increases from typically 17°BTDC@800RPM to some 34.5°BTDC@4800RPM. Particularly your maximum advance is substantially more than the textbook value of around 22°BTDC. Is this based on measurements, or tests on the ETZ250?
(Don't get me wrong: the more or less constant ignition advance you get from conventional systems is not necessarily optimal in my view!)
3) I would like to see a system that starts with very little advance at low revs (to prevent kick-back during starting), and then increases it's advance (to whatever optimal value found), up to a maximum RPM value (maybe 6500RPM for that bike?), and thereafter trails off rather rapidly to prevent engine damage. Have you done any tests in that direction: what is the maximum RPM, what is the maximum ignition advance, ...? Some dynamometer charts at various settings would be highly interesting, and would drive the choice of ignition curve.

So: Yes, a programmable ignition curve is very interesting: it allows further improvements & tailoring of the engine characteristics. The real work lies in determining what ignition curve is desired to create a particular character of the engine. Can you show something in that respect?

Thank you for complex answer. The graph you can see in my first post is from Kanuni factory in Turkey. Someone obtained this graph and put it on the internet.
As I wrote in my first post - tachometer shows inaccurate values. It is really 6500 rpm at the cut off. I changed the map a bit, when crankshaft exceeds 6500 rpm then the controller delays ignition to the same angle as at ~1000 rpm. I will describe some more details at the next weekend.

OK Jakub, thanks.

So your system has a programmable ignition advance mapping, and initially I thought that meant a pre-set ignition advance mapping, as given in the graph shown. Hence my questions on the basis of that graph. But it is also possible that your system is user-programmable, and that the user (= owner) is left to find & implement the mapping he prefers. IMO that would be more something for a racing team with unlimited access to a dynobank & loads of time, or maybe a retired hobbyist, but there might be other views.

Looking forward to your description of how your system works, and any information you may have on the effect of various mappings!

I use C programming language in my device. I can change the timing of ignition advance from 45 degrees BTDE to 0 degrees. I think it could by user friendly because you can save changes in flash memory up to 10 000 times. You only need to know how to do it. I use excel to convert real times to uC impulses.

OK, and what mappings have you tested, and how has your bike benefited from it, and what is the mapping you prefer? Dyno charts?

Or are you looking for people to test your system? ???