Yeah, I lived there for 3 years.
Awesome fishing, especially up the rivers. Papuan Black Bass is the hardest fighting freshwater fish in the world, and grows up to 25kg. I have seen guys busted off on 37kg big game gear (in the river, 12 foot dingy and game rods !).
I left at the end of 99. There was only a couple of bikes that I knew of. An old black BMW 65 ridden by a 70 year old German guy, a BMW K100 and a Yamaha TT600.
Would be an awesome place for some very serious cross county riding. The bush is riddled with snakes, all of the most poisonous Aussie ones, so care needs to be taken. Also the highlands get pretty wet and slippery.
Rumor was that it is possible to ride from Port Moresby to Mt Hagen on a mixture of 4wd and walking track. Would be bloody exiting, properly need to carry side arms, tho.
Cheers
Kim