I have a Kuwait air flight from kuwait landing at Istanbul on 14.35 pm and an Aegean air flight to Athens taking off from Istanbul at 16.00 pm from the same terminal. I am carrying only cabin luggage, so no need to retrieve and recheck luggage. Also I am having printout of online boarding pass for Aegean flight. So no need to go to the counter and get boarding pass. So even though, I am on two different tickets, on two different airlines, I can simply walk from the international arrival gates through transit area and go to the international departure gates, right ? Or does the customs clearance or immigration clearance come in between ? Is 85 minutes risky for this process ?