James had 31 points in the first half for Cleveland who have won nine their last 11 games and are 1-1 on their current five-game road swing.
Cleveland came out quickly in the fourth quarter going on a 11-0 run.
Brandon Roy scored 34 points to lead Portland, who have lost three of their last four games.
Martell Webster had 12 points for the Blazers.
Source: AFP American Edition