I have a drr 50 and it has me scratching my head. it rips until it gets warm and then kinda stalls for a second then comes out of it. I freshened up the motor, checked all wiring changed cdi stator, reeds, cleaned card real good. changed torque springs and rollers also.
though it may have been crank seals but it passed a pressure test.any idea?

 

Welcome to the forums.

Have you checked the fuel tank vent line for kinks or clogs?