Lahiri is now three-under for 36 holes after being three-over for 18.
Gaganjeet Bhullar, the overnight co-leader and a former Asian Games teammate of Lahiri, dropped to tied 14th as he double-bogeyed the final hole in near darkness on a rather turbulent day for him.
Marcus Fraser of Australia birdied the closing two holes to share the second round clubhouse lead with countryman Kalem Richardson.
Lahiri's presence in Jakarta also galvanised his young Bengaluru colleague, S Chikkrangappa, who five-under 67 to move seven-under and tied fourth place.
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Meanwhile, seasoned Jeev Milkha Singh, who turned professional in the year Chikka was born, carded a second straight 69 to indicate that he was still around as he totalled six-under and moved to Tied-eighth.
Lahiri had six birdies and no bogeys, while Chikka had six birdies and one bogey and Bhullar had everything on his card -- two birdies, an eagle, three bogeys and a double on 18th.
"I was hoping to come out today and be a little bit more positive and aggressive. It was good to get off to a good start. I hit 14 greens yesterday and 16 today so it is not that I'm hitting it bad. I still feel like I left two or three shots back. Hopefully if I keep this up, I can give myself a shouting chance come Sunday."
Jyoti Randhawa (70-72) was tied 35th and Shiv Kapur (68-75) and Rahil Gangjee (73-70) were tied 44th. Abhinav Lohan (72-72) was tied 59th.
Abhijit Chadha (71-74), Khalin Joshi (70-75) were on the borderline waiting to know their fate as more players were yet to complete their round.
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