Warin has a good answer to get you started:
- figure out how to get there - say $1000-1500 for a round trip air ticket, depending on your start and your destination airports, time of year, etc.
- figure out the cost of the vehicle. Are you going to rent, buy a small local bike, fly your bike in from overseas? A cheap little 125cc might cost $2000 US with paperwork and registration. Renting or buying might be a lot more.
- how much to take a tent, sleeping bag, etc.? How much are local hotels, according to travel guide sites? Even if you stay in cheap hotels, that gets expensive after a while, so camping will give you a lot more flexibility and save some money.
- food, fuel, maintenance will be lesser expenses, but have to be factored in. If your bike gets 50 mpg, and you ride 10,000 miles, that's 200 gallons at local prices $3 per gallon, more?
- miscellaneous: insurance, medical, park entrance fees, museum or other fees, etc.

Really, it's not rocket science to get a very rough ballpark estimate of how much cash you need. Grab a copy of Lonely Planet for South America or equivalent, get an idea of the rough expenses for daily travel, and you can build a rough spreadsheet from there of how much money you need.

Then remember this 'golden rule' for travel:
- put everything you think you'll need on a bed: clothes, camping gear, toiletries, and money.
- pack half the items...
- take twice the money...

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Bruce Clarke - 2020 Yamaha XV250