Sangakkara, displaying more aggression than his partner went to his 23rd Test hundred with a boundary off part time bowlerVirender Sehwag.
At stumps he had hit 15 fours in his 225-ball innings.
"We are hoping to post in excess of 550, which will put pressure on the Indians," Dilshan said after the last session.
India used six bowlers as they tried to stem the flow of runs, their only other success of the day was the wicket of Dilshan in the morning session.
But Indian batsman Suresh Raina, who is making his test debut, defended a depleted bowling attack missing Zaheer Khan and Shanthakumaran Sreesanth.
"We had a good bowling plan and did a good job. If you seen the approach we did really well," he said.
The Sri Lankan openers justified Sangakkara's decision to bat first by scoring runs briskly.
Dilshan attacked from the beginning, smashing Ishant Sharma for four consecutive fours in his second over and repeating the treatment on Abhimanyu Mithun.
Dilshan completed his half century off 39 balls with 10 fours but at 54 got over-ambitious. Attempted to drive left-arm spinner Pragjyan Ojha, he gave a simple catch to VVS Laxman at short extra cover.
Sri Lanka lead the three-match series 1-0.