The Whitecaps bats got going in the third inning when Brett Pirtle singled in two runs before scoring later in the inning on a throwing error, giving West Michigan a 3-0 lead.
South Bend responded in the bottom of the third with a run to cut the Whitecap lead to 3-1, but were unable to get any closer.
The Whitecaps extended their lead with a run in the fourth and two more in the sixth to take a 6-1 lead.
South Bend scored two runs in the bottom of the sixth. The game was called with two outs in the bottom of the seventh inning due to weather conditions.
Pirtle led the Whitecaps with two hits and two RBIs while David Gonzalez added an RBI of his own.
West Michigan starting pitcher Fernando Perez went four innings while striking out seven, walking three and allowing one unearned run.
Jordan Smith picked up the win for West Michigan, pitching 2.2/3 innings of relief while giving up two runs on four hits.
The Whitecaps will open up their home schedule at 4 p.m. on Saturday at Fifth Third Ballpark in Comstock Park against South Bend.