First of all, people will steal anything in this country that's not bolted down, or that is worth any kind of money, especially flashy american made vehicles and cell phones, and they might even steal your shoes and clothes too at gun point. My husband is Argentinian and had been living abroad with me and told me nothing every happens in Lanus, Buenos Aires, but a few weeks after we arrived here someone robbed him. They got his wallet, and all of his money, the stereo out of his car, and they even stole the shirt off of his back, and his groceries, so I definitely don't suggest wasting time, energy, or money on something that is really expensive here. It is likely to be stolen and you will never see it again. The police here are completely useless, just like in the states, but 100 times worse. They will not bother to help you at all. They are too busy with murders, kidnappings and other severe crimes.
Secondly, it's more hassle than it's worth to import something that is more likely to be stolen, or "lost", while in transit. Plus, you'd have to pay at least 50% in taxes of the bike's current official value, which will rack up expenses quickly. I've also had both locals and expats living in Argentina say they've had nothing but troubles with the mail services, like "lost" packages and letters, which are also likely to be stolen by people who are handling them in transit. So, wouldn't recommend risking something that expensive, unless you plan to sell it here in Argentina. Or, more preferably, if you don't plan to ever head back to the US, ask a trusted friend or family member to sell it for you and send the money via a personal bank account (if you're legal) or western union.
All that said, that's just what I've experienced personally here, so far, after a little more than a year of living here. I really don't know much about importing, taxes and duties, or paperwork for expats in Argentina. It may be different than it is for locals. All in all, I'd estimate you'd probably pay around, if not more, 25,000 pesos, or around $5500, just to bring it into the country, and that doesn't even include the local registration fees and taxes. If you really need it brought here then do it. It really also depends on where you live here. Tigre is the nicest place I've been so far in Argentina, and all the rich people live there, so it's a very upscale city.