i've got the 1.3s, though the 340 rockers seemed better. i hear that the champion clones run a cheap roller rocker. i'm just building the motor for now. this is a semi offroad kart, that will still be used for children. the parts are cheap enough to tinker a bit. on the stands, she runs 45 to 49, on the street she was runnning 35. i guess i don't have enough cam/carb for her to blow, which is great. my speedo went out, so no quantatative data till i get it replaced. sucks balls. when i did ride in it, i was driving with a passenger, so perfomance was not expected, neither did it show. the belt kept getting ate up to. i forgot to install a spacer.