But by the end of the first of four 40km laps, Cooper had powered his way up to second spot and he was closing in fast on the surprise early leader, local hero Mitch Rees (Honda CRF450F), of Whakatane.
Carter had suffered similar misfortune with his bike at the start and he was back in 60th spot but he, too, wasted no time in making up lost ground and was up to sixth spot by the end of his first lap.
The two Suzuki men worked their way even further through the field, eventually sandwiching King on the podium when the race was wrapped up after three hours of gruelling cut-and-thrust battling.
Carter was declared winner of the battle-within-a-battle for under-300cc four-stroke class honours, while Cooper easily won the over-300cc four-stroke class.
"It was pretty dangerous on that first lap with me being on the charge and with so many slower riders ahead of me," said Cooper.
"I wasn't just out there to do a parade lap ... I was pushing hard ... but, thankfully, lots of riders left enough room for me to fight through.
"I was riding sensibly, or so I thought, but it's just that what I call a 'sensible speed' is a bit quicker than what some of these other riders were doing."
It was an impressive performance also from the 19-year-old Rees, although he had to settle for fourth overall as his energy reserves ran out near the end.
"I knew fitness would let him down," said his former national superbike champion father, Tarawera 100 event sponsor Tony Rees.
"He got a great start and led the race for a lap. Imagine how I felt: I sponsor the event and my own son is leading it?
"None of the riders ahead of Mitch at the finish have to go to a proper job on Monday. They're all professional racers and Mitch finished as first amateur rider, so I'm very proud of him. He has now certainly finished higher that I ever did at this event."
Rees finished second overall, behind Cooper, in the battle for over-300cc four-stroke class honours.
Cooper, 28, first won the Tarawera 100 in 2007 but has now won it three times consecutively since 2010.
He switches back to motocross mode to continue his campaign across the Tasman, racing the Australian Motocross Championships.