"It's an honour to win today carrying Davey's number."
Cooper said he been "full of the 'flu" during the week leading up to Saturday's race and knew he would be short of energy. The unique race format, with four sprint races followed by a longer final moto, worked in his favour.
"I had to win the shorter races to get an advantage. I knew it would be hard in the longer race and at the end I was mucking up and not riding well. I pulled it back a bit to make sure I'd finish," said Cooper.
With four wins already on the scorecard, Cooper's third place behind Yamaha's Kayne Lamont (Mangakino) and Carter (Mount Maunganui) in the final moto gave him a clear overall win.
Carter was second overall and happy with his first race on his Kawasaki since breaking his thumb and collarbone in May.
"It was my first time back at the starting gate for about six months. It's good to know my speed is okay and I can still race," said Carter.
Cooper was the MX1 overall winner with 266 points over the five-race format from Carter on 246 and Rotorua's John Phillips (Honda) on 214.
Lamont was in podium contention after a 3-3-2 sequence in the first three races but crashed at the start of the fourth moto before climbing back to fifth overall with his final race win.
MX2 honours went to Taupo's Wyatt Chase (KTM) in a duel with Mangakino's Maximus Purvis (Yamaha).
Chase took three wins and Purvis two but a fall in race three left Purvis with a ninth place on his scorecard and trailing Chase by 18 points.
The closest Summercross fight came in the Youth MX (15-21 years) class where Taranaki's Ryan Gwynn (Husqvarna), Wairoa's Thomas Watts (Husqvarna) and Taupo's Jake Tomblin (Honda) each rode to a moto win. Gwynn edged Watts by five points for the overall win.
In his first start in the veterans ranks, Tauranga's Peter Broxholme (Honda) cleaned up the 35-40 years age group and Hamilton's Darryll King (Husqvarna) was unbeaten in the over-40 category.
A 29-strong field contested the women's MX races with Letitia Alabaster (Eketahuna) in command with an unbeaten performance on her KTM to take the Summercross honours ahead of Te Awamutu's Rachael Archer (Husqvarna) and Rotorua's Melissa Patterson (KTM).