But, the Black and Whites defence held firm as they only to restrict the hosts to a another penalty from Sinfield as the lead was 14-0 at the break.
At the start of the second half, the Rhinos extended their lead when England international Carl Ablett, backing up from Wednesday nights Exiles game, got his winger Ryan Hall over in the left hand corner. Sinfield's fourth goal from the touchline made it 20-0.
Hull threatened a fightback when stand-off Richard Horne touched down his own kick after the ball had squirted from the grasp of defender Ben Jones-Bishop and Joe Westerman added the conversion.
The score gave the visitors renewed confidence but they had given themselves too much to do and the conditions worked against them as they attempted to chase the game.
However, the only score in the last 27 minutes was a drop goal from Sinfield, as Leeds warm up nicely for next Saturday