BOSTON — Some Boston voters will be casting ballots for City Council.Tuesday, Sept. 8 is preliminary voting ahead of the Nov. 3 citywide election.But only voters in Districts 4 and 7 -- where Councilors Charles Yancey and Tito Jackson are seeking re-election to two-year terms -- are taking part.Most of Boston's 13 councilors are running unopposed.The neighborhoods voting include parts of Mattapan, Roslindale, Jamaica Plain, Dorchester, Roxbury, South End, Fenway and Mission Hill.