What documents to get bike into US from Mexico?
 

I'll be entering the US from Mexico by road in May. I'm a US citizen, but my bike is registered in Panama, where I live. This will just be a temporary importation of the bike into the US as I will be shipping it back to Panama. Anyone know what documents I need for the bike when entering the US?

Just to make it more interesting, I bought the bike in the US before moving to Panama. I still have the original bill of sale and copy of the Indiana registration. I don't know if that makes any difference, but should at least show that it is EPA legal.

I have been to the States about 5 times by bike over a 25 year period and never been asked to show any paperwork for the bike. I was never given any paperwork either. I have been perhaps 30 times by car and the same thing. Most of the time we have been close to the Border-San Antonio TX but have been as far away as Florida, Indiana, Colorado.
I am a UK citizen with Mexican residence and the vehicles have always been Mexican.
I always think that it is weird that I am asked for no proof of anything. A couple of times the vehicles have been searched and one time I had to open a pannier.
I have been stopped by the police twice- once for speeding (on a bike) and just showed my license and registration and the other time in Laredo in a new car which had a "permiso para circular" which is a temporary permit to be able to use the car. The cop wanted to check that it was still valid. What he would have done if it had expired I don't know. He new exactly what it the "permiso" was and spoke to us the whole time in Spanish.
Obviously it may be different in your case. Hope that helps.