The race started strongly for Whibley, taking his Yamaha YZ450F to the front at the start, before being pegged back by his Yamaha team-mate Jordan Ashburn, who slipped past for the lead soon after the riders passed the pit zone.
"I was riding a little tight and wasn't really flowing with the track early on," said Whibley.
"American riders Charlie Mullins and Thad Duvall slipped by before we had completed the first lap. I was trying to loosen up and not pump up by pushing too hard. I was following Thad when he went down when he spun over a rock in the track. I moved up to second when Jordan went down in a rocky creek as well."
Series leader Kailub Russell then made his presence felt, passing Whibley shortly afterwards.
Duvall, for his part, had recovered quickly and was soon looking for a way past Whibley. Going down a hill toward a checkpoint, Whibley clipped a tree and was sent over the bars. He was up quickly and back into it but soon discovered the bike had suffered more than himself. The bars were a little bent, but worse was that the rear brake lever had been bent under the engine casing.
"The next time I braked, the lever stayed down and began dragging. I stopped and tried to fix it, pulling it out from under the cases, but I couldn't manage to straighten it enough to prevent it happening again," Whibley said
"I continued that lap without using it and stopped in the pits for a quick fix. I was a long way back when I rejoined the race and the time I had lost to the leaders was going to be a big ask to make back, but I put on a charge to try to salvage some points."
Whibley soon passed Japanese Takashi Koikeda, then Chris Bach. The laps were winding down but he was still putting in some good times. A quick splash of gas and he also chased down Jordan Ashburn and moved by fellow Kiwi Rory Mead late in the race.
"Getting into fourth position was a solid finish, considering how far back I had been and at least I was earning some points," Whibley said.