Fogarty led in the early stages of the first race before being passed by Kocinski just after half-way in the 26-lap race. The British rider held a safe second place before slipping off with four laps to go to leave Kocinski's team-mate, Aaron Slight, to take second with Kawasaki's Simon Crafar completing the top three.
Kocinski led from the start of the second race, but lost the lead for seven laps to Crafar before powering his way back into the lead on the 14th lap and victory never looked in doubt.
Fogarty was hit by the Spanish Ducati rider Gregorio Lavilla on the opening lap of race two before bouncing back and climbing from 21st to 11th place, only to crash for the second time in a day, on the 16th lap.
Fogarty's failure to finish either race gives Kocinski a commanding lead with just two rounds remaining in the 12-round series.
"Winning races is important and I knew that I could win here, but to open up a lead like I have done is a dream," Kocinski said.
"But the championship is by no means over and I've now got to concentrate on winning in Japan and Indonesia next month."Reuse content