ETZ125 with MZ-B generator/magneto-HELP

[emzedhed]

Hi this is my first post. I've just bought the ETZ125 with MZ-B that was on Ebay last week. It seems basically sound but won't run properly and I suspect the timing is out. I know nothing of it's history so if you do please tell me! I got it from a gent in Cleethorpes who'd had it a month. The battery has had it but I understand it doesn't need it anyway. Do you just remove it and tape up the wires or what? The neutral light is not working . Could that be connected? The rev. counter is not working but the cable and instrument are OK, The bit the cable fits to on the engine doesn't turn and seems quite stuck-the bit with the slot in it. What now? I think I understand how to retime it, although I don't have the puller. Does anyone live near Gainsborough or Lincoln?

[djsbriscoe]

MZ-B has instructions somewhere on the interweb for these systems. Dave will be along shortly with a link I'm sure.
Does the rev counter drive turn when the engine is running? If not there is something wrong with the drive gear (on the clutch somewhere I think). If you search the forum for the MZ workshop video's (or search on google video's for MZ MAINTENANCE) you will see where the drive gear is.

[emzedhed]

Thanks for that. I don't think it does turn when the engine is running, otherwise the rev counter would work-it does slightly when I twiddle the drive cable with my fingers. I think it is a worm drive which will be why it is 'stuck' as you can't work them backwards and the little wheel is not turning with the shaft. I've found an exploded diagram which gives an indication of what and where it is. Thanks again.

[emzedhed]

Well, I've adjusted the timing via the backplate, using a strobe lamp and that wasn't the main problem. The bike starts and will rev up a bit but not fully. Probably about 3500rpm from the sound of it. Itried resetting the needle height to 2 from the top and it wouldn't really go at all even with choke. With the needle a couple of slots higher it will run with choke. It'll run without for a while but then it starts speeding up and conks out. I suspect the needle was even higher before I removed it, I don't know because it all fell out. It begins to seem that maybe the crank seals have gone. Can anyone confirm my diagnosis? The bearings sound fine and compression is there, at one point this afternoon it was ticking over really slowly, which made me think it couldn't possibly be the seals, but the carb was set very rich so maybe it still is.

[DAVID THOMPSON]

note mz-b.de has sold the mz parts supply's biz to a place in hungry and it uses the mz-b.de web site

the site for the electrical stuff for many bike brands is now

http://www.powerdynamo.biz/
there are drawings there for the systems
dave

[djsbriscoe]

Have you checked that the jets are the standard size? While your doing this you could check the float height. Adjusting the needle only affects part throttle response and should not affect idling. Best to set the needle at three from top. Lowering the needle (from 3 to 2 from top for instance) will lean the mixture and vice versa. Is the carb a BVF or a Bing? Not sure how you check for healthy main seals, maybe you can smell the gearbox oil to test for a petrol smell?

[emzedhed]

I've given up for the moment until I get a manual. How do you set the float height though. Haven't noticed what type of carb. It's an '89 g-plate bike. It's leaking creamy brown gear oil from the kickstart shaft when it's running so maybe that's an indication of shot seals. How much are a pair of seals and where's best to get them?

[webhead]

hi dude you can get seals from burwin,s or from ebay ,or from a proper bearing and oil seal supplier ,just take them out ,easy on a 125 as there on outside ,dont have to split engine,start clutch side ,lefthand thread on crank normal on clutch nut,there only cheap seals ,go for a double lip seal and make sure its very high temp they last for ages then ,if you check clutch side ,you can soon see if its cream crackered ,as it will spin with finger usualy ,they must fit tight ,and make sure you put new 1,s in same way,it easy ,and then it should start first kick aslong as carb is clean timing is ok,if its been sat your best to replace them as seal would have shrunk..

forgot to say size is on seal itself so easy to find.
have fun