In late 1982 Karpun, and other Tampa Bay reservists received their first international experience when they trained for two months in Brazil with the world renowned club, São Paulo FC.
[10] His strong indoor play, coupled with rapidly shrinking NASL budgets, earned him a call up onto the Rowdies first-team roster midway through the 1983 outdoor season.
With the collapse of the NASL immanent, Karpun signed with the expansion Dallas Sidekicks of the MISL in October 1984[12] prior to the 1984–85 season.
This reunited him with several people from his time in Tampa Bay including Tatu, Wes McLeod, Perry Van der Beck and head coach, Gordon Jago, the man who had originally signed him to the Rowdies II squad.
[17][18] In Dallas Sidekicks history, Karpun ranks fifth in goals (146), seventh in assists (76), and eighth in games played (249).
Beginning in 1989 Karpun spent several summers playing outdoors with his hometown Vancouver 86ers in the Canadian Soccer League.
[21][22] He first played in the return leg of a 1983 Olympic qualifier versus Mexico on November 23 at Royal Athletic Park in Victoria, British Columbia.