i don't belive the claculator for speed is right cuz i ran my ratio thru it not to long ago and it daid my max speed was like 30 mph, i have a 60 t sprocket and a 12 t clutch, im running a jack shaft also with a 12 t on the motor and the 11 on the shAFT therfore making my rpms go up from 3900 to about 4125 sumthin like that, anyway i clocked my miles an hour today and i went 50mph. i have an 300 sumthin cc 11 hp honda four stroke motor. this kart is also capable pf donuts and stuff anyway. givce me yur input thanks