Such was the visit that George Thaung, the 89-year-old behind one of Canberra's best known late night food spots, received on Tuesday.

The tattooed stranger, who identified himself only as James, had been one of the homeless Canberrans that Mr Thaung had fed for free when the Mandalay Bus operated in Braddon during the 1980s.

Having turned his luck around in the mines at Lightning Ridge, James returned to repay Mr Thaung for his generosity with two opals.

''He had no home, no food,'' Mr Thaung said.

''He never forgot it.''

Mr Thaung's son Stewart said he was reconditioning the bus when the-then unknown James appeared and asked if his father still owned the Burmese food outlet, located in Haig Park at the end of Lonsdale Street.

''He knew where dad lived,'' he said. ''The next thing you know, he's at our door.'' Mr Thaung said the gift, thought to be worth hundreds of dollars, was presented decades after James and his father last met.

''It must have been more than 20 years ago,'' he said.

The visit came little more than a week before the grand opening of the revamped Mandalay Bus, which coincides with Mr Thaung's 90th birthday on December 30.

Stewart Thaung said he and his business partners had been working on restoring the old Sydney bus, which sat mostly unused since Mr Thaung lost an eye following a fight during a Summernats weekend in the early 1990s.

While there will be some new things about the outlet, including artwork by local street artists and dishes by Soju Girl chef Andrew Hollands, Mr Thaung said the character of the bus would retain the generous spirit his father had fostered.

''That's going to be the essence of it, to keep it as part of the community and look after the people that may be hungry,'' he said.