This is complicated, so take note.
Arrive at border early (8 o' clock). Saturday, Sunday, no go. Aduana gone fishing.
Go to Colombia Migracion, on left. Get salida stamp. Go to aduana next door. Be told that you have to go to main aduana near Cucuta airport (some 10 miles back). Don't try to find it. When in town, hire a taxi, who will take you there for 2,500 pesos. Present yourself at their office. An old geezer will go to bike with you and take a rubbing of its serial number. Done that, your free to leave Colombia. Back to border.
First go to Venezuela Migracion across the bridge in town (San Antonio). From the border post some four to six blocks into town, turn right for some 8 blocks, ask. Get your tourist card and entry stamp. (No longer necessary to get this at their consulate.) Go back to border post (remember your route, bec. you have to come back).
Next: Get photocopies of all your documents nearby. Go to aduana at your right when entering Venezuela. Present your originals and copies. She will ask if you have international insurance. You say yes, because you do. Your American or Canadian bike insurance is good in both countries, therefore is international. She types out your document, which will cost you 6000 bolivares ($3.00).
Next: You must go to Transito Police, on same block as Migracion, but around the corner. Watch for one-way streets. Go to photocopies across the street. Copy all your documents. Present these to Transito. One of the boys will endorse your aduana document on the back and enter your details into a book. You're free to roll in Venezuela. No one will ever stop you or check on you. But please note: Aduana closes at 14.00. So don't dawdle. Check my note on money. This is why we think adventure biking is a lot of fun.