Ahhh the famous Pierburg 2e2 carburettor, known for being ultra reliable and easy to work with, no...wait...that's wrong.
Most people will recommend throwing away the Pierburg and getting a weber. Fair enough but personally I enjoy fixing stuff and once you sit down and learn what each part of this carb dose, it soon becomes a lot less daunting.
So what problems have you got? Fast idle? Stalling when warm? Running too rich? Flat engine? Over run? High fuel consumption? One of the biggest problems is that some one in the past may have tweaked this and tweaked that to try and make it run better. This is a nightmare because now you don't know what you're dealing with.
You may have several of these problems, I know I did! If you have played with anything without knowing exactly what your doing (like I did) then you need to go through checking everything and only when each stage is set will you have a carb that works.
Lets start with the most common issue, FAST IDLE. This will almost certainly be caused by the WAXSTAT. A new one is going to cost you over £100. Either the waxstat has failed or its not getting a decent flow of hot water.
There are two types of waxstat or (expansion element) one is metal body and a newer version in a black plastic body. The black plastic version is supposed to be more reliable but personally, I hate 25 year old plastic that's been baked over a hot engine.
Now, although this may be faulty, it might not be passed it. First we need to see if the water flow is ok. Start her up and feel the auto-choke housing (on right hand side of carb), this should get hot quite quickly. When hot, feel the waxstat, this will most likely be hot too, GREAT! If you cant get much heat from the choke then you have a blocked coolant channel.
So if we find good water flow to the waxstat we can now go in for a closer look. If you remove the unit and find a grey powder its likely to have leaked and now no longer of use to us. If you remove it and can see no signs of leakage then its time to test it. Avoid pushing on the pin or pulling it out!
Run some hot water through the body, the pin should now start to extend. If it doesn't then you can try immersing the unit in a cup of boiling water, this will reform the wax inside and might get it going again. If after all this you still cant make it do anything, then, Im sorry to say, its had it. However if its working and extending a fair distance then we can fit it back on, I would use some lube on the pin and on the piston it acts apon in the carb itself. Its also worth checking the cam it operates as there is an adjustment. Only adjust it if it appears to have been played with in the past.
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