I ran old skool 15, 15.5, 16 and 13/16 skats on my 650 setup and liked the 13/16 best. as stated above, the 9/17 c75 would be best on the 650. Off topic - save your money and get a 750. night and day difference, I cant believe I waited so long to do the swap. Not just saying that cuz I have a...