Thermal cracking in a riser cracking, closed cyclone, fluidized catalytic cracking process is reduced. A snorkel or flow conduit having an inlet just above the catalyst stripper moves stripper vapor into the closed cyclone. The system preferably operates without a stripper cap, relying on fluid dynamics to isolate stripper vapor from upper parts of the vessel containing the riser outlet. Preferably the snorkel is at least partially supported by, and ideally is inside, the primary cyclone dipleg. Reduced residence time of stripper vapor in the vessel containing the stripper and the closed cyclone system reduces thermal cracking of stripper vapor.