Puerto Paez/El Burro Border from Venezuela
I've just spent the last couple of days trying to work out how to get from Venezuela at El Burro/ Puerto Paez, to El Carreno on the Colombian side. I'm yet to make the crossing, but after two days asking people I believe this is how to cross at that point of the border.
First you need to go to Puerto Ayacucho to do the paperwork for yourself and the bike. The building you are looking for is virtually unmarked, it is on an industrial estate near the airport (I only found it as I hailed a taxi to get me there). Opening hours are 8am - 4pm (I just missed it yesterday..and am now having to wait out the weekend in Puerto Ayacucho). Puerto Ayacucho is the last place you can get cheap petrol so fill up.
Having completed the paperwork travel to El Burro via route 2 (approximately 50 miles). Here you must get a ferry to cross to Puerto Paez, it's a short crossing it takes just 5 minutes and costs 10bs. There is a single road of about a mile taking you towards the small town. The road continues but you must turn off and take the unmade road through the town which will be on your left. Follow this for about a mile, through the town (it twists and turns a bit). You will eventually arrive at the river. Here a boat leaves a couple of times a day for Colombia. The area is a bit sketchy, so keep an eye on your bike.
I hope that this helps someone else do a crossing off the well trodden routes...I'm hoping for fun roads to Bogota on the other side! Venezuela has been amazing so make sure you visit if you are in this part of the world!