The Dunedin dynamo had already notched 16 victories in a row, going into the first two rounds of the Sandpit Series in Invercargill and Cromwell and added wins in all three races at each of those rounds.
Deciding to up the ante and test his skills on some unseen tracks, Cuthbertson elected to miss the final round of the series in Balclutha last month and travel across Cook Strait to race.
He competed in the 12 to 16 years 85cc to 150cc class at the Wellington Motocross Championships on July 21 and won his three outings on his four-stroke, Honda CRF 150cc motorcycle.
The following day he rode at the Mighty Manawatu motocross meeting, near Foxton, in the junior under 17, 85cc and 150cc class and extended his consecutive win count by another three races.
In the feature race, it looked like his luck had run out when he crashed on the first corner.
However, his father, Grant, said Cuthbertson picked himself up and despite being "dead last", chased down the pack and took the lead on the second lap, to score successive race victory number 29.
Asked to explain his phenomenal form, which stretches back to the tail end of the New Zealand Junior Motocross Championships near Timaru, in April, Cuthbertson attributed it to putting in the physical groundwork.
"I've been doing a bit of fitness training and I all of a sudden started stepping it up and lately, I've been just going faster and faster."
He has no end target in sight for his winning streak and the Otago Boys High School Year 10 pupil plans to keep clocking up "as many as I can".
Leading results for Otago riders for the Sandpit Series included Josh Hurring, of Balclutha, who was runner-up in the 12-16 years 125cc/14-16yrs 250cc class and Tom Scurr, of Wanaka, eight points behind him in third. Madison Latta, of Balclutha, finished third in the 12-16 years 85cc class.