ETZ 250 crankshaft problem

[christensen]

Hi, to all members of this fabulous forum, this is my first post on this forum and it comes with a problem

I put a short description of my motorcycle:
I own a MZ/ETZ 250 from 1988. After I’ve bought it in 2008 I’ve start to modify, special for more reliability… the electronic part was in the first plan … rewiring, changing the turn lights and park light/stop light into led’s(diy stuff), ignition unit ( I changed the old ignition unit (ignition coil, mechanical contact breaker, condenser) for a Opel Astra F(16NZ) ignition coil, Hall sensor(TLE4905) and a mosfet final drive) and the original carburetor to a Mikuni. All those modification are not for show of and I’ve keep the original outside esthetic, for example the LED’s lights cannot be noticed just only when are ON, the covers of turn lights and park/stop light are all original I’ve build from scratch all those modules (all those I will present in other topic).

And back to my main problem:
When I bought the motorcycle was in a good condition, esthetical and mechanical but after a few months later it begin showing the hidden problem, start with the crankshaft bearing, at high engine revolution (when it reach the maximum torque) some noise come out from engine(the feeling was similar with rev limit).I’ve think something is wrong with the piston head, so I take down the cylinder but all was normal, surprised clean(I use full synthetic oil). When I’ve changed the ignition signal pick-up on the crankshaft I’ve notice an ‘up and down’ movement of the crankshaft, this movement was produced by the ‘tired’ crankshaft bearings. When I’ve open the engines I’ve noticed the reason for the main bearings was ‘out of service’, the crankshaft and the clutch had been modified and wasn’t centered properly and generate an irregular clutch rotation which damage the bearings and produced that noise.






Now I need to buy a new one but don’t know which I should choose from those (I need to change both crankshaft and the clutch):
1.
http://s40205778.shoplite.de/sess/utn;j ... shopscript

Kurbelwelle ETZ250/251 -NEU => 75,00 € (Bestellnummer: 00302)

Kupplungskörper TS/ETZ250 => 31,50 € (Bestellnummer: 40587A)

2.
http://www.ost2rad.de/MZ-Ersatzteile/Zy ... Z-250.html

Kurbelwelle ETZ 250 / 251 / 301 => 117,00 EUR (Art.Nr.: 590)

Kupplungskörper MZ 250 => 24,70 EUR (Art.Nr.: 1031)

3.
http://www.oldtimerteile-haase.de/produ ... 51_301.php

Kurbelwelle neu - ohne Altabgabe => 105,00 EUR (Bestell-Nr. 12307)

Kupplungskörper ORIGINALERSATZTEIL => (MZ-Nummer05-44.153)33,50Euro (Bestell-Nr.12410-3)

Had someone ordered from those online shops? Which of them are better, because I see the price are quite different…. or perhaps you know a better shop?

ps. you can replay in german language, i use google translator and it is quite good.

Thanks in advanced!

[hiha]

Hi Christensen,
I bought my last clutch-body at ost2rad, and my last ETZ-crank at "Motorrad Ente", it was about €100.-. But AFAIK all of them sell out of the same source, if they sell Aftermarket-cranks.
I recommend to give the new crank to a specialist, let it press there with a bit more axial clearance at the bigend (~0,3mm), because the 0,05mm my crank had, seem to be to small.

Gruß
Hans

[christensen]

Hi, thank you for the quick answer.

I'm concern about the aftermarket components of this days , what I know that the aftermarket components for MZ are made in Hungary, Turkey and Korea(the last one I’m not sure …. Somewhere in Asia).i had some problems with new tachometer/speedometer cable and the chain pinion cover all of them had very poor quality and besides that isn’t fit at all without modification.

I’m not sure if exist a tuner company for MZ(I mean that the company make the crankshaft not only are resellers or modify an existing crankshaft ).

[Guesi]

Hello

The crakshafts are all made in Taiwan.
But they are quite good quality.
You can also have GDR-regenerated crankshafts, but I don`t think they are better.
Nowadays the tools are better and the precision of production is more advanced than 20 years ago.
I sell these cranks very often and had no problems yet.
Some of the other reproductions,plastic and rubber especially, are partially very poor quality , thats right.
But that is also a problem of the customers, because many are not willing to pay good money for good reproductions.

[christensen]

Yes Guesi, you are right concern the customer wish to pay as less possible and doesn’t mater the quality! And that’s for all consumer goods! But in my opinion is much expensive/ annoying buying a poor quality component than a better quality, there are the cost of servicing and time spend on it(if you are doing by yourself). I don’t search for a cheap crankshaft, I don’t have time to disassembly the engine every year because I choose a poor quality component!

For example I had a really bad experience with my speedometer, when I bought the motorcycle and I was in the way to home and the chain had jump off from the back pinion and destroy all the covers from chain/pinion , the speedo cable and the speedometer as well. After that I bought few speedometers but non one had reliable and I spent a lot of money and time on those .. till i realized that in the end is better to start from scratch and build a digital one.

[Ralle]

Some of the other reproductions,plastic and rubber especially, are partially very poor quality , thats right.

I can see a better quality chain pinion cover for example in your shop guesi. Price ist only 5 € more than the poor quality product money well spent.
From my own expirence I can say, that guesi ensure a good quality for the most products he sells

and the chain had jump off from the back pinion and destroy all the covers

It is intentional that teh chain pinion cover brakes, if chain is jumping off from the pinion, otherwise the rear weel could block...

[Guesi]

Its interesting that most people tell me the same than christensen .
But when it comes to buying most people take the cheaper parts.
Isn`t this weird ?:-)

GüSi

[Ralle]

[ot]I´m not one of "most people" [/ot]

[Guesi]

[ot]Yes I know. You are the saviour of the serious dealers..

GüSi[/ot]

[Ralle]

[ot] For this heavy job I do not buy often enough [/ot]

[Cika Dule]

Hi christensen,

What scares me is that hole between the crank cone and the needle bearing.

In addition, the edges of the needle bearing plastic cage seems to be burnt, which leads me to conclude that clutch has been revolving around the crankshaft cone previously in some time. It should be that someone drilled this hole in order to place some appropriate steel part in it to prevent clutch "skating" around the crankshaft cone.

From those reasons, it seems obvious that crankshaft and the needle bearing is to be replaced as well as corresponding parts.

Under my opinion, it would be enough to purchase only the clutch top plate. So you cold combine other parts of your old clutch with it. It is quite recommended to use grinding paste to adapt both clutch and crank cone quite precise. Afterwards, mount them together after you make them clean from any dirt and grease.

Hope you understood, and it's of some help.

Regards,

CD

[christensen]

Yes, you are right about the reason of the hole on the crankshaft, the previous owner made that because the clutch had slip on crankshaft. This method is pretty often use by many people, because they don’t tighten enough the clutch assembly (with the engine assembled completely is not possible to develop a force of 90Nm on the nut, it need to lock/secure.. the piston) .

yep only the clutch top plate I want to buy, beside this the clutch other parts are in good condition.

Thanks

[Christof]

You are rigth. You have to tighten the clutch on the Crankshaft with a torgue of 90Nm before assembling the clutchcover. Otherwise the clutch may jump of the crankshaft. But before you dismantle the clutch, please mark the Postion of the Toothring, the clutchplate and bearingplate to eachother. After removing the clutchbody assemble these parts with their old position.

[christensen]

Hi,
Today I had change the crankshaft and i've prepare to assembly the engine but unfortunately i've lost the Thrust washer (19 - Anlaufscheibe)orig part no. 05-44.138.

Could somebody tell me the size of Thrust washer? I only know the thickness 2.3mm(from service manual).

mzclutch.gif

Thank you in advanced.