leaving the bike in southamerica for a year,
 

my wife and me are planning a tour from Southamerica to Alaska, but we cannot do it in one trip, so we have to leave the bike for 9 to 12 months in different countries in South and Middle and northamerica, everybody tells us, that this is impossible. I do not believe this. Do you have any answers and tips?

Mr Everybody is full of it as usual. BUT he is technically correct. Take your vehicle in - take it out is the rule

Many countries give a 90 day tourist visa and a 90 day TIP and look the other way when you fly home for a couple of months. BUT don't overstay the TIP or else.

US supposedly allows only 12 months for the vehicle and that includes time in Canada and Mexico. You can get a visa that allows up to 6 months at a time in the US. Going to contiguous countries does NOT reset the clock.

Canada you can fill in a form 99 at the port of entry and apply to be able to leave the vehicle for up to a year. They may charge a refundable deposit.

Mexico doesn't seem to care if you leave your vehicle behind for up to the normal 180 days. They charge a refundable deposit when you enter. (motorhomes can get a 10-year TIP)

Many overlanders leave their vehicle in Uruguay for up to 12 months because that is how long the TIP is normally valid for - but note that in some circumstances it is only for 90 days. US$50 per month for a large vehicle http://parkingenuruguay.com/

In Argentina, usually get 8 month TIP but again, some borders give only 90 days Around $50 a month for a vehicle, but a couple of motorbike storage places charge super-rip-off prices. Andeanroads.com probably store bikes as well as large vehicles at a reasonable rate. They have basic camping facilities as well

We left our camper in Peru for 8 months by getting the TIP suspended on medical grounds. Expensive storage at Quinta Lala $4 per day

In Ecuador we got a 6-month visa (expensive) and then got the TIP extended to match. Storage costs $1 to $2 a day for a large vehicle. No problems with leaving vehicle up to the 90 day limit of the TIP BUT be aware that Ecuador allows only 90 day cumulative TOTAL personal visa in 12 months from the date of first entry and then will give you another 90 days. Most other countries give you another 90 days every time you enter but there are exceptions. Bolivia is particularly stingy, but will give extensions.

In Panama (I think it is) you can leave your vehicle in bonded storage for $1 a day - not in Panama city which is expensive, but at a country aduana office.

Brazil is a special case supposedly. Don't give TIPs any more and some take that as meaning you can leave your vehicle there forever and just come back under a new visitors visa and take it out without problems. Yet to be proven though

Of course some of this may not apply in your case since you don't mention your nationality. Room in your profile for that and a bit more info