He was beaten by Shannon Blake, from Napier, also riding a CRF100 Honda.
"It was a bit of a buzz. I just love the sport. My idols are my dad, who raced motocross and Chad Reid, from the USA, and Ben Townley," McKinlay said yesterday.
Townley is a former national and world champion in the 450cc class and was again a winner at Woodville at the weekend.
McKinlay said: "Even my teachers know how much I love the sport, they buy motorbike books to make me read."
Mum Jo said the weekend racing had heightened anxiety levels a tad, with older son Trent (14) also competing on the day. He finished 19th of 40 in his grade on his CRF150 Honda.
"Grant has raced for some time, but put his hobby aside to help the boys get a start. He makes sure they get used to their bikes before stepping them up to more powerful machines. It was a bit nerve-wracking with both boys racing at the weekend," she said.
Drew McKinlay is no stranger to national honours, having won last year at a national meeting hosted by the Wanganui Motocross Club, of which he is a member.
"That was on my first bike, a CRF70. I turn 12 in March, so move up a grade for my next big meeting in New Plymouth in October, but I hope to have a different bike - my brother's CRF150," he said.