Alfie Davidson powered to the top of the combined timesheets with a hot lap of 1min 41.474secs, leading Cameron Dawson by 0.751secs.
Harley McCabe was third quickest, with Ollie Walker fourth and Ted Wilkinson fifth.
Pirelli British Sportbike Championship, combined practice:
1. Alfie Davidson (Aprilia IN Competition Racing) 1min 41.467s
2. Cameron Dawson (Powerslide Racing) +0.751s
3. Harley McCabe (Fibre Tec Aprilia by Mlav Racing) +0.953s
4. Ollie Walker (Wight Morgan Ollie Walker Racing) +1.134s
5. Ted Wilkinson (TWR Ted Wilkinson Racing) +1.245s