As an amateur, Asiku represented Uganda at the 1998 Commonwealth Games in Kuala Lumpur, Malaysia and won a bronze medal, losing to eventual gold medal winner Richard Sunee of Mauritius. In 1999, he won a bronze medal at flyweight in Boxing at the All-Africa Games in Johannesburg, South Africa, losing to eventual silver medal winner Nacer Keddam of Algeria. In 2000, he took part, in the Summer Olympics in Sydney, Australia, losing to Arlan Lerio of the Philippines. During his amateur time, Asiku boxed in flyweight.