03 predator 500

I have a 2003 Predator 500 with a CFM airbox and an HMF exhaust and headpipe. Does anyone know what jet i should be using? HMF wants a 155 for its exhaust but when I put my CFM airbox on without an exhaust it ran real lean. I'm a bit new to the predator platform and any jetting tips would be...

I was riding my predator one day and it ran perfect. I parked it that night and the next day it wouldnt start. I cleaned the carb and put a new spark plug in, it still didnt start. I took the airbox off and the fuel is being sprayed out the back of the carb into the airbox. Please help!