Points opening too wide

[keleto]

Hi all. My bike is a 1994 ETZ251 which (I think) was converted from electronic ignition to points at some time by a previous owner. God alone knows what MZ the points cam came off but it seems in good condition. No rust or obvious distortion. The points cam is nicely located in its tang and sits well. The stator is properly located on the crankcase pin and the rotor is properly located on its crankshaft peg. I have got the (new) points opening perfectly at 2.5mm BTDC with a home-made dial gauge. At around TDC the gap is fine at the specified 0.3mm, THEN after starting to close up the points whack open to about 3mm wide for about 1/4 of the whole cycle. (I can post pics or a video if anyone doesn't believe me !!). **It runs fine*** but this configuration must surely be putting a lot of wear on the points heel and strain on the spring, and has left me confused. Any advice would be appreciated.

[keleto]

OK an expert has suggested that the rotor is not sitting well on the crankshaft as the carbon commutator slip rings seem to be running eccentrically, I will explore this angle....

[Blurredman]

Did you find the solution to this???

I also have a similar issue, I cannot get the points to open at all at the firing point unless the points are 1mm open on the 2nd opening. ...

[Lone-Wolf]

Wotcha.

It could be a case of cheap, nasty, pattern parts.
I bought some new points and could not get them to open enough.
The plastic "heel" was the best part of a millimetre too short.

[Blurredman]

That is certainly interesting, However I compared my problem with two sets of points:

One was a set of points that was on my other MZ that worked perfectly fine and opened properly, the other set was a brand new old stock ddr set that i got given which was notibly longer and yet had exactly the same problem again. It's like the lob is wrong in it's degree angle.

[AlanJ]

Hi Guys, Just had a look at your 2 pics and it would seem not to matter what the dim is where you are measuring from, ie the part of plastic you are measuring doesn't matter how thick it is. Should the dim be from the points gap to the heal, or am I seeing it wrong. Take care Alan.

[Blurredman]

Right..


I spent two hours on this today and my investigation got me absolutely nowhere.


I have two MZ ETZ 250's (one of them a 251- the one I am having problem with).


First I took the stator and rotor off. The rotor key was in the exact same place on the crank and so was the position on the magneto/rotor.

I installed EVERYTHING, rotor, stator, points, cam etc from the 251 onto the 250, I could set it all up succesfully to the specified gap and able to open the points in the appropriate position before T.D.C fine. It worked perfectly and was easy to set up. As it should be.


I did the same to the 251 with the 250 parts... EXACTLY the same problem I have consistently been coming accross, for the points to open at all at 2.5mm before T.D.C the points gap needs to be 1mm on the other side!!! I am at an absolute loss as to why this is happening. Not funny! I've changed all the parts. No matter how long the foot on the points are, or what ever angle the stator plate is, the same result occurs.




In the meantime, this is apparently a full set for conversion and I am likely to buy it.. http://mz-b.net/etz-universal-coil-puls ... 0000098460

[Lone-Wolf]

Wotcha.

I went down the electronic ignition path in the end . . . .works just fine.

http://www.themzshop.co.uk/product/elec ... torcycles/

Easy to fit and set up - more than happy with the results.

[Eric Frith]

That's the system I fitted to my bike and it's absolutely superb, retains the original generator and is a piece of cake to install.

[Blurredman]

Just to let you know the only realistic (and easy) way of getting around this issue was for me to buy an electronic ignition as described in this topic:

viewtopic.php?f=5&t=8526


I will be doing the timing tonight.