I had occasion to nip up to Boa Vista recently. I decided to go by bike and risk the vagaries of the BR174, and it turned out okay in the end. Total return trip was just over 1,600km, achieved in 23.5 hours. The only crap bit was from north of the indigenous reserve to the town of Caracarai, with 200km of mud, potholes and roadworks.
It was a good test for author and bike, and the next journey planned is to Porto Velho to the south. This is around the same distance, but the road (the BR319) is much worse.