As I mentioned,  it came off a B&S on a Craftsman mower.  I bought a new (Chinese) carb on Ebay-  a direct replacement for the original,  and it didn't work,  so a friend gave the Dosens.  At least the engine runs in it,  just not correctly.  I'd never heard of the Dosens either;  seems to be reasonably good quality,  good Amazon reviews.  I don't know what to do with it.  I can't think of any reason for the problem other than carburetion. 
 
 
Rick A