The 22-year-old has also been fine tuning his body with 5.30am gym sessions and a personal trainer.
Jarman works in the family business at Tamaterau Engineering, which helps defray the costs, but hopes to find a major sponsor for the championship.
In December, Jarman won the two-stroke class at round two of the Auckland Motorcycle Club Championship at Hampton Downs racetrack. He got a first and a second onboard his Honda RS125 to take first overall.
Fellow Whangarei racer Duncan Coutts also had a successful weekend at the Auckland races in December, winning both his races in the pre-89 post classic class.
He is coming second in his class after two rounds of the championship.
"I had some bike issues at round one and missed qualifying and a race," said Coutts. "But I've managed to close the gap from 35 points difference down to 21 and, with three rounds remaining, I hope to chip away at it."
This weekend's nationals include three rounds in the South Island which will be followed by two in the North Island in March.