No Runtime!!!

Hey guys I have searched the forums to find some help with my problem.
I need help. I have an ofna hyper 7 and here is the setup mm speed control feiago 7xl motor and a 123 batteries. I have a 16 tooth pinion on the motor and the buggy runs fine,(very fast) my problem is it has no runtime my battery setup is 4s2p and the runtime is less than five minutes!!!! With a 13 tooth pinion the run time is about 20-25 minutes... I have a hyperion charger 610i duo to charge the batteries. I have them hooked up in the buggy in parallel. What tooth spur is in the hyper 7? Am I that much overgeared?