hi guys,,, theres quite a few guys in the yamaha xs650 club of australia,, that have rephased their motors,,the guys that seperate and weld it /balance it..and i,ve ridden 1 ,like this method ,,,, it sounds like a ducati which is niceeeeeee.... they nearly all recton that with direct pull carbys and cam ,they are getting up to 40%more torque at the back wheel,,, the guy from maffra ..i rode his yellow rephased home made crank set up ..moved 3 splines.. along with a home made electronic ignitionand that sounded lovely and heaps of grunt his yellow xs650 is on the australian web site.... and the ex club president is an old hand at rephasing/caming/chopping /and playing with different carby set ups mostly direct pull .. thos guys will all help you with info as well ... hope this helps you regards oldbiker