I was in school in Germany in the 80s, so this book must have been in the early 80s or in the 70s at least. I only remember fragments, like people live in utopian suburbs with white picket fences and clean streets, controlled weather so that it only rains at night and is always sunny every day. The metropolitan areas are walled off, dark and dirty, and the outsiders, criminals and homeless people are left there to struggle. A kid from the utopia wants to go into a city just to see what it's like and experiences a life view changing adventure. I've been trying to find this book for years, but I can't remember the title or author or even if it was exclusively German or originally English.
Based on your description, the plot seems to match some elements from the novel "This Perfect Day". I was able to track it down with a search engine so I don't have actually read it, but most points match.
The book describes an artificial dystopia where weather is controlled so that it only rains at night and indeed the protagonist is a child. That said, there are also differences: the kid grows up during the story (so he is not a kid anymore at the end) and the "outcast" live on "islands" where they are isolated so that they cannot represent a threat to the dystopia.
The publication year could match too, the story was published in 1970 - so it could be reasonable for you to have read it in the 80'.
Reminds me somehow of Futuretrack Five by Robert Westall. But I haven't read that book since the eighties so I'm severely shaky on the details. Something about taking aptitude tests to see what you would work with for the rest of your life and not getting too good grades because then you're drafted into the secret police or something.
And everyone who's not an elite lives in shantytowns and ruins or something. I'm sorry... very shaky recollection. Think there was weather control.
Also there were mind reading helicopters I think...