It'S not that easy.......
If the Bike is US spec and was purchased here, shipped abroad and then brought home again.... No problem.
HAve the exporter of choice ship the bike and bring the title and registration to customs when picking up.
Dot and EPA have made it very difficult to import a non US sold Bike. If the bike in question is the same spec, has the same emission components and meets US EPA emissions restrictions then you must acquire written confirmation from the manufacturer that the bike does indeed have all the specs of the US equivalent export. If this is not acquired and the bike is shipped it will languish in customs and will be assessed exorbitant storage fees until such paperwork is acquired.
If the bike is to be imported for off road use only "Racebike" It must be proven to be "not road worthy" or capable of registration. Taking the Lights off, removing the horn, adding race body work will not qualify the bike as race only. a 17digit vin will disqualify any attempt at claiming that the bike is a "race bike".
If you intend to still try and bring the bike here and have no written confirmation from the manufacturer , you will have to arrange compliance with a certified importer/compliance provider that will accept the bike at the port of destination and make the bike compliant with all DOT and EPA regulations. IT may not need anything but it must go through this "middle man" and he assesses his fees even if he does nothing to the bike.
If the bike is a true race bike (Usually 10 digit vin) you can have the bike shipped via an exporter to your preferred port and then claim the bike from customs (Bring exporter's bill of lading and ID) and you will be assessed a 3% fee as duty.
Same if the bike is over 25 years old. This is an "antique" and can be imported, made road worthy and registered for road use as "collectible"
In the event that a imported "race only" bike is registered and found on the road. The EPA/Dot will institute a fine up to $25,000 /unit to the individual who imported the bikes.
Basically they make it damn near impossible and certainly unaffordable for the average American to import
any vehicle that is intended to be used or sold for road use.
If it's not a 2 stroke GP bike...Prototype or over 25 years old...
Sell it and start fresh at home.
Oh and they used to allow an individual to bring in one personal vehicle (3% duty) from a foreign country (applied mostly to military) but have long since closed that loop hole.
So much for fighting for "American Freedom"
Canadian bikes are subject to the same rules above though it's quite a bit easier for a Canadian bike to enter the country as a "race bike" in the back of a trailer. There are ways to cheat but if your caught, the fines are prohibitive.
Coming from overseas.... You have to have your T's crossed and I's dotted.........and jump hrough a host of hoops.
Or you can disassemble and ship as "bike parts" but you better not have the motor complete........ It's whats subject to all the EPA/DOT crap
Or ship the rolling chassis and put a US power plant in it after arrival
I know that this is far from complete and that some generalizations have been stated so that I don't sit here typing all night but this is pretty much what you'll face when trying to "import a vehicle"
SO....
Good luck