Brazil 319 is not a secret road, but it is 300+ mile of dirt, many dodgy bridges or water crossings and no gas stations. Riders report camping out at the cell phone relay stations for safety from animals at night. The total distance from Manaus to Porto Velho is 550 miles, but there is a gap in gas stations in the middle. I think it takes riders a minimum of 3 days, but usually longer. Getting gas, food and fresh water is a challenge.
Check the annual rain fall pattern and schedule your ride during the dry season. I met a French rider who rode BR 319 during the wet season. He told a tale of mud and dropping the bike more times than he ever imagined.
I have never ridden this stretch of road, but have been long fascinated by it. If I get the chance, I would like to do the opposite and take my time, making it a 7 or 10 day ride. Not sure if there is much to see that would capture my attention or of it is practical given the lack of services (needing to pack in water and food.)
NYC to Tierra del Fuego (and back!) 2012/2013
Blogs: Peter's Ride