From the second row of the grid Kinsman raced to the front in the final after a battle with points leader Daniel Bray and Graeme Smyth (both Auckland).
''I haven't won the weekend overall but it's always good to win the final race,'' said Kinsman.
Aucklander Bray made a fast start from the outside of the front row and led the early laps of the final. Smyth passed him on lap seven with a move that would count for nothing as he was one of three drivers excluded post-race for passing under yellow flags.
The overtaking practice that Kinsman had gained in his back-of-the-field starts came to the fore with a neatly judged inside move into the first turn that put him ahead of Smyth on lap 12 to stay in front through the second half of race.
After Smyth was excluded, Bray regained second after holding out Hamilton's Rhys Tinney is the closing laps. With three wins and two second places earlier in the weekend Bray was the overall round winner on points to extend his lead in the ProKart series with three of the six rounds completed.
Bray's NZed Motorsport team also had success in two other categories.
Jared McKenzie (Auckland) was a clear winner of the KZ2 Masters final and Auckland's Nathan Crang was another to deliver a back-to-front effort to win the Rotax Max Junior class.
Crang had missed Friday practice sessions due to a school exam and he didn't figure near the front of the Saturday heat race results.
An eventful 25-lap final saw Dylan Grant (Auckland), Gemma Winters (Te Puke) and Clay Osborne (Hamilton) all take a turn at leading in a fierce fight but Crang was the big mover with an impressive drive from 10th spot on the grid to join the lead battle and hit the front with four laps to go.
The top Junior points scorer was series leader Riley Spargo (Rotorua) who was only sixth in the final but had a string of first and second placings through the heats and pre-final.
Aucklander Gary Cullum won the KZ4 final and Tauranga's Darren Walker consolidated his lead in the Rotax Max Heavy series, winning the final and top-scoring overall for the weekend.
Manawatu driver Jackson Rooney won all four Rotax Max Lights heats, slipped to fifth in the pre-final and then raced back to the front in the final to lead home Ashton Grant (Auckland).