It was a classic battle of power versus height and Teki-Clark remained composed throughout, using his superior reach expertly to prevent Sykes doing any damage.
The other Rotorua boxer in the finals was relatively inexperienced rising star Matua Parkinson, of Rotovegas Boxing Gym, who had been dominant in his few amateur fights leading up to the champs.
He went up against Auckland powerhouse Sonatane Tautalanoa who had about 35 bouts under his belt and has fought in international competitions.
Parkinson showed plenty of heart but Tautalanoa's experience showed as he won via 'referee stops contest' in the third round.
Rotovegas Boxing Gym owner Aaron Warren said Parkinson had never done three minute rounds before but put in an admirable effort.
"The other guy won fair and square. I thought Matua lost the first round, won the second and sort of gassed out there in the last.
"There's nothing wrong with losing. He lifted to another level and it humbles him a bit, he knows it.
"He did all the basics right, but made a few mistakes like dropping his shoulder too often. The focus for him was to box three rounds and try and win every round, he left everything in the ring," Warren said.
Championship supervisor Keith Walker, who has been involved in six Olympic Games through boxing, in different capacities, said all the fights this week had been evenly contested.
"The boxing this year was very good, I think the competition was very close. Generally we have one or two who really stand out and it makes it difficult to get an even balance, but this tournament has been very competitive. That's been a real plus.
"Those who won medals have had to work hard - that shows you the level of competition that we have," Walker said.
He said the standout boxer on the night was Wellington/Hutt Valley's Ryan Scaife, who was awarded the Jameson Belt for most scientific senior boxer.
He produced a technical masterclass to claim the elite 75kg title against Auckland's Francis Waitai.
"We also had a family who came from Hungary in January this year and both boys won medals. That was a highlight, to have two boys come from another country and box in our championships for the first time."
Walker said Rotorua was "a great host".
"[Championship organiser] Rex Jenkins and his family are absolutely an asset to this city and everybody enjoys working with them.
"They get great support from coaches and from boxers and I think that speaks volumes of the people themselves."
He said the performance of the junior cadets on Thursday night was promising for the future of New Zealand boxing.
"That's always been our big plus, our cadets. They go through cadets, juniors, then youth, then elite and our best boxers, like Ryan Scaife, started as a kid in the cadets. They grow with the sport."
Despite having attended boxing championships all over the world, Walker said it was "always good to be involved at home".
"I started boxing when I was 10 years old - I'm now 76 and I haven't left the sport."
New Zealand Boxing Championships title winners
Junior Male 70kg - Viliama Hakalo (South Auckland)
Junior Male 75kg - Onyx Lye (Auckland)
Junior Male 90kg - Livia Fauea (Auckland)
Youth Male 60kg - Tui Vea (Auckland)
Youth Male 64kg - Tyreke Nicholls (South Auckland)
Youth Male 69kg - Michael Reynolds (Wellington/Hutt Valley)
Youth Male 75kg - Szilard Laszlo (Wellington/Hutt Valley)
Youth Male 81kg - Sonatane Tautalanoa (Auckland)
Elite Women 51kg - Katie Thompson (Central Auckland)
Elite Women 54kg - Marea Motu (South Auckland)
Elite Women 60kg - Troy Garton (Shamrock)
Elite Women 64kg - Cara Wharerau (Kirikiriroa)
Elite Women 75kg - Che Kenneally (South Auckland)
Elite Men 52kg - Ryan Entese (Canterbury)
Elite Men 56kg - Rendz Remaneses (Canterbury)
Elite Men 64kg - Richie Hadlow (Otago)
Elite Men 69kg - Callum Owen (Otago)
Elite Men 75kg - Ryan Scaife (Wellington/Hutt Valley)
Elite Men 81kg - Sunny Teki-Clark (Canterbury)
Elite Men 91kg - Frank Masoe (South Auckland)
Elite Men 92kg - Sam Watt (Canterbury)
