Riding his Rapid Solicitors Kawasaki machine, Byrne finished more than four seconds ahead of Yamaha rival Josh Brookes in the first race with James Ellison on the podium in third.
Brookes’ team-mate Tommy Bridewell was fourth, ahead of BMW rider Riyuchi Kiyonari on the BMW, with Chris Walker finishing in sixth position.
The second race was far more of a spectacle with Brookes going clear of pole-sitter Byrne on the opening lap.
The pair swapped the lead several times during the early stages of the race with Bridewell and Ellison close in behind them.
But on the 13th lap the Brookes suffered a huge high-side at the exit of the Montreal corner while leading. The Australian was able to get to his feet but the crash allowed three-time BSB champion Byrne to go clear.
Ellison and Bridewell were locked in the battle for second but Ellison came out on top to claim his second podium of the day, finishing two seconds behind Byrne.
Bridewell finished third to claim his first podium of 2014 with Kiyonari and Frenchman Julien Da Costa completing the top five.