The hosts carry a 2-0 lead into Wednesday's third ODI in Hambantota, where the reserve day on Thursday could come into play with Sri Lanka's rainy season once again expected to be a factor.
A blistering century by Moeen Ali and 65 from Ravi Bopara saw England make a good fist of chasing down 317-6 in the opener to the seven-match rubber in Colombo.
Finn returned from injury to bolster the tourists' attack at the same ground on Saturday but there was little for them to work with as only Bopara passed 50 in a paltry effort of 185 all out.
In a match nominally reduced to 45 overs per-side - England fell two short of using their allocation - Kumar Sangakkara and Mahela Jayawardene sauntered to unbeaten scores of 67 and 77 respectively with more than 10 overs to spare, leaving under-pressure captain Alastair Cook and his team with plenty to ponder as next year's World Cup in Australia and New Zealand looms on the horizon.
"We need to front up and get out there and face everything that's put in front of us," Finn told a press conference. "If we can bat as we did in that first ODI I think that's a great template for us going forward.
"As bowlers, we need to adapt to conditions better - I think as a team in general we need to adapt to conditions better.
"That's something that we can keep improving on and keep working on. It's about being smart when you're out there on the pitch and training smart beforehand to prepare you for the conditions you're going to face.
"That's something that we can keep improving at but I feel like we definitely are moving in the right direction."
Finn bowled with lively pace on his way to 1-35, providing one of few bright spots for England last time out - the rangy Middlesex man offering the latest demonstration that the form collapse which cut short his Ashes tour last year is firmly in the past.
"I felt like I bowled well the other day," he said. "I feel happy with where my rhythm's at, I feel happy with where my bowling is at.
"I'm hoping that, as we go through this series, I can grow into that role even more."
Jayawardene will sit out the match, meaning Thilina Kandamby is poised to come into a team that fellow middle-order batsman Lahiru Thirimanne predictably reports to be brimming with confidence.
"We had a good match last game so the boys are really looking forward to this match. Confidence levels are really high," he told reporters.
"Mahela is normally our backbone because he strengthens up our middle order but this is a good challenge for the young players.
"We have to replace him some day so this is a good opportunity for them to show what they are capable of."
England all-rounder Chris Woakes is expected to be fit having suffered with an upset stomach over recent days, with Ben Stokes and Chris Jordan providing alternatives to the Warwickshire player.