The Devils were indebted to Morten Risager and Sam Simota, who contributed 27 of their points between them with a welcome return to form, including six of the team’s eight race wins.
Team manager Lee Trigger said: “It was good to get back to winning ways and brilliant to see Morten and Sam step up to the plate as they have been struggling of late.
“Morten has spent some money on his bikes during the week, going back to basics and it has paid off for him.”
Plymouth operated the rider replacement facility for number one Ryan Fisher, who was ruled out after suffering concussion in last week’s Knock-Out Cup clash against Somerset.
Plymouth: rider replacement for Ryan Fisher, Morten Risager 13+1 (6 rides), Jack Holder 6+2 (5), Todd Kurtz 7+1 (5), Kyle Newman 9+1 (5). Reserves: Sam Simota 14+1 (6), Matt Bates 1 (3).
Workington: Kyle Howarth 9 (5), Rusty Harrison 2+1 (4), Rene Bach 7+1 (4), Kenneth Hansen 5 (4), Ricky Wells 12 (5). Reserves: Matt Williamson 2 (3), Matthew Wethers 3 (5).