Final orbital periods of recycled radio pulsars as a function of their CO WD companion masses for systems evolving from helium star donors with a metallicity of Z = 0.02. Data points connected with a green line were calculated from the same initial helium star mass (1.2 M_⊙ and 1.4 M_⊙, respectively). Data points with black dots were all calculated from a binary with an initial orbital period of 0.1 days. The solid red star and the open purple star, connected with a black line to the green data points, indicate similar calculations including an applied hypothetical kick velocity of 50km s^-1 and 450km s^-1, yielding the widest possible orbit. The less massive the initial helium star donor, and the more narrow the orbit, the more material the NS accretes and the faster spin it obtains. The dashed lines indicate roughly where the pulsar is spun up to 15 ms and 80 ms, respectively. See text for discussions.