Transfer from Haneda to Narita Airport?

HI, there,

We, a group of four from Malaysia will be travelling to Hokkaido in July 2015. Our return flight JL511 fly Sapporo to Haneda Terminal D1 and connect JL711 fly Narita Int'l Airport to Singapore on the same day. My Question is we have 3 hours 30 minutes from ETA to ETD, is this sufficient for transfer from Haneda to Narita? Apparently we have to exit Haneda A/Port and check in at Narita A/port, with the immigration and custom clearance at both Terminals. And do Check-in-luggage to check all the way to Singapore at New Chitose A/port?

Hope to hear from you,

Thank you

Yengkee

Very tight, but I think it's viable. I would use a bus that goes directly to Narita: 

http://www.limousinebus.co.jp/en/bus_services/narita/haneda.html

You will have to make transfers if you use the train with all your luggages. On the other hand the bus will take you directly to the airport in about 75min.

i agree that it is very tight. JAL usually have a good punctuality with their schedule, so it is possible. The limousine bus is best. http://en.japantravel.com/view/haneda-airport-to-tokyo-and-narita