I got a carb from a friend of mine. It needs to be rebuilt and upon taking it apart there are a lot of whtie deposits and that kind of stuff. I am assuming that it is in those small passages... How do I clean those out?

 

Carburetor cleaner... soak it if the deposits are heavy, then blow out the passages with the little straw on a spray can of cleaner, and afterwards flush them with compressed air.

 

I have also used plain white vinegar soaks. it cleans up a lot of metals including taking off the rust from steel after 2 days of soaking.
With carbs I soak for a few hours, rinse, and blow out with compressed air nozzle. I have thought about neutralizing the vinegar after the soak but have not done that yet.
The vinegar really cleans much better than I though it could.