Oldnwiser
XS650 Enthusiast
I am sure that the XS2 has a better cam but I wonder about something. My father-in law had an XS2 that he would ride alongside mine before I tore mine down and did a top end with an overbore some Shell Thuet pistons, lightweight pins at 700+ ccs and my own tricks , a 3 angle valve job and a minor blend into the Short- Side Radius that yielded a bunch. It settled the ports down so the flow and velocity were better matched. And the valve job was based on 45 degree angles but I put a 30 degree angle backcut to make the off the seat flow double and they flowed really well by .300-.400. Anyway my father-in-law’s bike never ran with mine. I don’t think it had been swapped for a later engine. The EPA in the US required a milder cam for 1973. Does anyone know if this possibly was applied to some 72s late production?
I also put the XS2 cam I had in mine after the top end and it was very strong. Does anyone have the real specs of the XS2 at the beginning of the model year and the 1973 EPA. US camshafts? Mine ended up making more torque than hp at 2800-6800- and was less than peak torque at 7500- but it may have made more if I had gone to 8000-8500. It felt like it was just getting going at 7500. Anyway I would like to get the specs between the two. I increased the CR to 9.25:1 by surfacing and thinner gaskets and those 3 fork oversized pistons from MrThuet seemed to have a higher dome and good quality cast reliefs. Thank you!
I also put the XS2 cam I had in mine after the top end and it was very strong. Does anyone have the real specs of the XS2 at the beginning of the model year and the 1973 EPA. US camshafts? Mine ended up making more torque than hp at 2800-6800- and was less than peak torque at 7500- but it may have made more if I had gone to 8000-8500. It felt like it was just getting going at 7500. Anyway I would like to get the specs between the two. I increased the CR to 9.25:1 by surfacing and thinner gaskets and those 3 fork oversized pistons from MrThuet seemed to have a higher dome and good quality cast reliefs. Thank you!