In his first year of racing, in 1931, Milliken won the 20 miles (32 km) Victorian road time trial, covering the distance in 53' 45".

In 3 consecutive years, 1931,[1] 1932[5] and 1933[12] Milliken set the fastest time in the Colac to Melbourne 100 miles (160 km) amateur road race, and in setting the fastest time, Milliken won the Victorian road championship title.

of 4h 11' 47" and what was claimed to be the world 100 miles (160 km) competition record of Frank Hose of 3hr 46' 25" set in the 1931 Camperdown to Melbourne race.

[16] Milliken won the 129 miles (208 km) Goulburn to Sydney in 1932 [4] and twice set the fastest time, in 1932 [4] and 1933.

[33] After turning professional in 1934 Milliken was narrowly defeated by Fatty Lamb, with Hubert Opperman in 3rd place, in the Batman 1000 a race over 8 stages in Tasmania covering 1,000 miles (1,600 km) starting in Launceston and finishing in Ulverstone.

Stage 5 was marked by torrential downpours of rain hail and sleet as the riders climbed Mount Buffalo and Milliken suffered a puncture and had to wait more than an hour for a spare wheel.

[34] In 1935 Milliken was part of a team, led by Opperman and organised by Bruce Small, that travelled to England to attack various distance records.

Other team members were Hefty Stuart, Harold and Eddie Smith, Joe Walsh and New Zealand's Hubert Turtill.

"[27] In 1938 Milliken rode in the Barnett Glass Grand Prix of 160 miles (260 km) however he crashed and did not finish.