Hey so ive been traveling the past few years and have to be home back to seattle in 6 months. I wanted my return home to be from the pan American road. So if i start from the bottom of argentina would i be able to just buy a bike and all my gear somewhere over there? And i really want to get there immediately but was told the weather is really bad in july. When does the weather clear up? And is it still ok to ride bike in bad weather if i just man up?

Argentina is not the country to buy a bike as a foreigner as it is illegal to take it outside the countries border and motorbike parts and accesories are very expensive in Argentina. Chile is not a good country either as it is illegal to take a vehicle out of the country as a foreigner (unless you have recidency)
From what I have heard and read Colombia or Peru are the best places in South-America to buy a bike as a foreigner.
But if youre talking about buying a bike from another foreign traveller with foreign plates this could be done more or less everywhere but it will be very difficult to get the bike in your name and it will get you into potential troubles crossings borders.

Weather in Argentina in July? Can you define «bad weather» first maybe? The southern hemisphere has the opposite climate from the northern hemisphere, thus July would normally be the coldest time of year. Argentina is a huge country and very long, actually more than 5000 kms from south to north. So the weather and climate isnt exactly the same all over the country.
If youre thinking about Ushuaia I think the best period will be from December to March, other than that you would potentially have very cold weather. Hey - I rolled into Ushuaia christmas eve 2016 and it was 3-4 degrees celcius and sleet in the air. It wws fresh snow down to 100-150 masl in the mountains around Ushuaia.
I rode northern Argentina in July last year and in was nice and warm except one day that was a bit chilly. I also rode northern Argentina in early June this year and it was pretty cold most of the time. Had to stop in a small town for 3 nights and wait for better aka warmer weather. So it can differ a lot from year to year and from south to north, west to east.

__________________
In the end everything will be fine. If its not fine its not the end....

Cheers for the info bud. Im gonna try and hold off till august or july. And hopefully find an American ending the trip and selling their bike sounds like the best bet

I think it may be difficult to find many foreigners finishing a trip in Ushuaia in August. That is the end of winter in the southern hemisphere. Very few people plan there trip thru Patagonia during the winter. Roads thru Chile and Argentine (such as the Careterra Austral) are very difficult in the winter, snow and freezing temperatures being the biggest hurdle.

Most travelers from the U.S., Canada or Europe try and arrive in Ushuaia between January and March. That is when you will have the best luck in finding a used foreign plated bike. I finished my trip in Feb of 2018 and met several people along the way who wanted to sell their bikes when they reached Ushuaia.

A good source for finding people already on the road is the facebook group Pan american travelers association.

There are many US plated bikes for sale in Southern chile or Argentina. You just have to get them reregistered in your name, either by yourself if you are from USA or Alex Smith can do it for you if you are from elsewhere. Just leave Argentina or Chile with old registration and enter the other country with the new one.

Harder to sell after March down there.

__________________
Alaska 2014: Hotel Budget ZeroXmas in Death Valley, New Year in Urique