Help... My Zundapp is not happy

So I have a sweet 1978 Zundapp ZR20. Since I have owned it, it has done some strange things and I dont know where or what to start with to fix it.

It seems to run very slow for a moped.Maybe it tops out at 15 - 20.

Then sometimes I will get a little push and it goes to about 25 - 30.But if I let off the gas,it wont go back up to that speed unless I get another push.

Recently I have had a leaky carb and very oily soot in the mufffler.

I did a carb clean and rebuild. But I am not sure if the spring is being compressed to hard for the reason of the cable being old or the wrong size?

So the carb went back on and now it feels like it is either getting to much gas of to much air?

I would say gas

I also noticed that when I put in a new plug.After one start and run. It was covered in soot and oil.

I mix 50 to 1

When I turn the air screw. Nothing happens.


I know that I have nothing but question

Re: Help... My Zundapp is not happy

Probably Fred /

Sorry there is very little of these bikes in the states so I can tell you the usual stuff .

Got good gas (petrol) flow?

Carb jets clean? correct jetting and complete airbox?

Exhaust clean can you blow through it?

Good spark? Timed correctly?

Clutch good?

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