Northern Rivers trainer John Shelton has won many big races in his local area and beyond but none bigger than the $1.3 million Kosciuszko at Randwick.

Punters disregarded Belflyer's second in the Ramornie Handicap at Grafton in June and sent the sprinter out at $71 on Saturday.

But Adam Hyeronimus and Belflyer didn't look at the odds and the seven-year-old stormed home to beat Suncraze ($15) by half a length with Awesome Pluck ($9) another short neck third.

"This is my biggest win by far," Shelton said.

"I've won the Ramornie and several races in town, not enough mind you, but this beats everything.

"I had confidence he would handle the ground and this is great.

"I love this horse. He's a special horse. For Adam to win on him was a really big bonus because he was apprenticed to me and we've remained really true friends."

The Kosciuszko runners were chosen by people who bought tickets for the right to have a runner in the race modelled in part on the Everest but for country-trained horses.

Shelton left the negotiating to co-owner Troy Hogan and slot holder Thad King.

"We were looking for a horse that could come from behind because we thought there would be a bit of speed on," King said.

"We were keen on him from the very start and he's proved us right. Johnny Shelton - what a legend!

"We're so pumped.

"We're in the horse for the rest of his career. Surely he's back here next year? Surely someone is picking him for next year."

Hyeronimus gets few opportunities in big races and was thrilled to be in it let alone win for Shelton.

"This is so good. To ride it for John makes it even better.," he said.

"I was apprenticed to John for the start of my apprenticeship. Ever since I left Grafton, to this day we speak every day.

"After the Ramornie things probably didn't go his way in races. I went to ride him in Brisbane one day and things didn't quite work out but he still ran good.

"John has done a perfect job with him. He knew he was ready to go and he was so confident in him.

"The biggest thing John said was 'don't get there too early'.

"As it panned out I was there at the furlong. He was going up and down and I'm bouncing all over his back. I looked up and thought 'c'mon, where is the winning post!'

"Everything worked out though."