I have made lots of B50 strings, but I want to build some d97's. Will I need special serving for that or can I use what I have?

You could probably use what you have, but it will need to be built up some.  I usually build 14 strand dacron strings.  When I build a 12 strand D97 I use ff serving, which is thicker.  The nock fits the same.

Like said you can use any serving you have or want to use.I make all my D97 strings 12 strand with two extra strands in the loop ends and I use .024 Halo serving.I like the Halo serving because the larger diameter and it is slick and strong.That combo gives me the nock fit I like.12 strands D97 is strong enough for up to a 100# bow so it will handle any bow you have there.

I was thinking of trying one of O.L.'s skinny strings...not sure if I am brave enough to go 4 strands, but thinking maybe 6 would work.