100" bolt in from an 88", S&S 585 easy starts, Do I go with the S&S 89cc head and mill them to 85cc to keep 10.5.1 comp or Do I street port my factory heads with 190in/161ex valves with 585 springs.....I keep thinkin the 2" valve in the S&S heads will be to much for lower rpms.....possible velocity problem....Oh and this is a S&S Super E carbed bike

 

Have no idea which would make more power but suspect the difference is not enough to offset the greater cost of new heads and milling vs sending yours out

 

Work with your heads.

 

I have S&S 89CC heads. The casting had some slag. I ended up sending them off for porting.
You're better off having your stock heads worked. It will cost less and have better results.

 

have your heads ported,do a full port job too.not just a street port (pocket port)

 

If you do decide on the S&S heads the 79cc would be a better fit. The casting on the set I had looked better than the 89's.

 

Have the heads worked too the cam... Porting does differ based on cam selection... I know quite a few builders here like the 585's and will do you right... Kirby/Scott...