A first set advantage of 6-2 for Riga, who welcomed England international Mike Percival back into the fold, was wiped out as the visitors won 15-9.
The second set followed a similar pattern and Riga were hit by injury to Ben Bunn as they lost 15-12.
And the Yorkshire outfit again overturned a Riga lead in the final set for another 15-9 scoreline.
Disappointed skipper Tom Young said: "To say we weren't at our best is an understatement, we just weren't at the races."
