Four Canadians - two plastic surgeons and two lawyers - have bought 190 acres in Plains, Ga., with the plan of picking up the Carter tourist trade, and the hope of getting to know the American President.

"Probably about 2 million people will go to this area, and there isn't much to do there after you've walked up and down the main street once or twice," said Harry Zahoruk, a lawyer from Burlington, Ontario. For their entertainment, he and his partners are considering putting a "creative playground," a "rustic restaurant," camping facilities and a Canadian-American friendship house possibly featuring Carter memorabilia, on the site, which adjoins Billy Carter's property.

They are calling it "Jimmy's Backyard."

Zahoruk, who says he feels "Mr. Carter will make a great President - he's vaguely reminiscent of Mr. Kennedy," has also bought an acre and a half facing the President's property. He is building a "Southern Colonial house" there, in which he plans to spend two or three weeks a year vacationing, and will rent the rest of the time.

"Probably I shouldn't quote her, but Miss Lillian did say, 'Jimmy'll drop in and see you - he drops in and sees all his neighbors,'" Zahoruk said. "That alond is worth the price."

The larger property includes a 5-acre manmade lake which the Canadians have named Lake Amy, and Zahoruk said he was pleased that the President's mother has requested permission to continue fishing in it. The permission was granted. She had apparently fished there when the land was used for the cattle, and, before that, as a peanut farm.

The others partners are Walter and Robert Sorokolit, brothers who are both plastic surgeons, and Paul Tokiwa, a Japanese-Canadian lawyer. They own six other properties together, in Canada and the United States.

Zaharuk has also bought 41 acres near Plains with other partners, which they are thinking of re-selling.

The plans for "Jimmy's Backyard" are tentative, he said, but "We wouldn't plan anything plastic or stainless steel. We want to keep it in the turn-of-the-century style of the area. It won't be an amusement park or a carnival, or anything like that." He hoping that a corporation will sponsor $1 million worth of playground facilities.

"We're not speculators - we're sentimental," he said.