Why Wont 5hp Briggs and Stratton start?

Ok i had this motor on my go kart. i had a header on it and a fire sloted head also. i was driving it hard for awhile and the rod broke in 5 pieces and the piston warped and messed up the crankshaft . So i put new rings in it and a new rod and cranksaft. The motor has good fire and the valves are not sticking i tried pouring a little gas in the carb. the motor turns over good it ran fine before i blew the rod. I cant get the motor to start i have no idea why.the gas in the carb is oily to i dont know if its a valve guide or what. Could i have installed the rings wrong i have no idea,.... Any help would be appreciated