First-round co-leader Erik Compton posted a 3-under 68. He stands alone in second place at 8-under-par 134. Rob Oppenheim and Steve Scott each notched rounds of 3-under 67 to share third place at minus-7.
Hearn ran off four consecutive birdies from the 11th to climb to minus-5. He then parred his next four holes to remain there, including a key par-save at the 17th of Pine Ridge Golf & Country Club.
Around the turn, Hearn again drained four birdies in a row from the second to get to 9 under. He parred his final four holes to close a streaky, but bogey-free round.
'When you have it going, those par saves can be the most important,' said Hearn, who won the Times Colonist Open two weeks ago. 'I very easily could have dropped a shot there at 17, but instead I built on the momentum. It really didn't matter what anyone else was doing today, I was just focused on my own game. Erik is on quite an impressive run himself, so it sets up for an exciting weekend.'
Compton birdied two of his first four holes. He parred six holes in a row before a birdie at the 11th. He followed that with a bogey on 12 and a birdie on 14 to move into second place.
'I'm just going to go for it on the weekend,' said Compton. 'All you want is a chance, and I've put myself in position to do that. It sounds like a cliche, but I am just going to take it one shot at a time and hope it all adds up at the end of the week.'
Dan Swanson, Todd Tanner, Peter Wilson, Clint Jensen and Stephen Woodard share fifth place at 6-under-par 136. Dustin Risdon and Russell Surber are one stroke further back at minus-5.
The cut line fell at 1-over-par 143 with 62 players making it to the final two rounds.