Snowbum's BMW Motorcycle Repair & Information Website

http://www.clearedanddelivered.com/article/CD-Help/15/import-a-motorcycle-to-the-usa
https://wittymelon.wordpress.com/portfolio/importing-vehicles-into-the-u-s/#:~:text=Luckily, there is a 25,be exempt from EPA standards

http://www.epa.gov/otaq/imports/factmtop.htm   From this, you will see that excluded vehicles are those that have been excluded from the emissions requirements of the Clean Air Act.  Exclusions are for age, type of fuel, maximum speed, or lack of certain safety features.  Excluded vehicles can be imported by anyone, withOUT Customs bond or bond required by the EPA.   Motorcycles built before 1978 are excluded!

There is an exemption for vehicles 21 years or older from the original production date ....do read how that is interpreted.  The importer must file an EPA form 3520-1 upon entry, declaring code E.  Customs may require proof of age.   Note that the vehicle must be in its original unmodified configuration (you may have to figure that one out for your instance).    Note that if the engine was replaced, the vehicle is not eligible unless equivalent or newer EPA certified.  I think that leaves a lot of wiggle room!

One could interpret EPA as meaning pre-1978 needs only paperwork; pre-1981 needs a letter from the EPA (see the website).

There are some other things you NEED to read in the document.

Dealing with your State's DMV is another story entirely ...whether importing from another country ...or simply from one State to another within the 50 United States.  I may be able to offer specific advice for California, maybe Canada, eventually, etc.

Exporting to another country may be simple....or, complicated.   The vehicle may have to have insurance before it is imported; it may well need an inspection, possibly more than just title, serial, VIN, etc.... by some sort of government entity upon importation, possibly even before it can be driven on the new country or State roads.   You might have to supply special documents.