Buchan Bishopscourt Superbike win
Buchan won from Gearlink Kawasaki rider Ben Wilson, with Andy Reid from Jordanstown third on his first Superbike ride on the Milwaukee Yamaha.
James Egan, Alastair Seeley and Jamie Hamilton made up the top six.
Glenn Irwin, who set a new lap record in winning the Supersport race, crashed unhurt while leading the Sunflower.
The Carrickfergus rider came off on the opening circuit of the 12-lap race.
Buchan won the first Superbike outing of the day from Wilson, with 2013 Irish Superbike champion Nico Mawhinney completing the podium.
Irwin was followed home in the first Supersport event by fellow Carrickfergus man Seeley, with Wilson third.
Irwin was also victorious in Supersport race two, with Wilson runner-up and Seeley third on the Mar-Train Yamaha.
Reid fell off unhurt in Superbike race one while Christian Elkin took the chequered flag in the opening 125cc/Moto 3 outing.