850 double pump issues HELP!!

ok well went to preformance shop guy told me to take 45 power vavle and put in prim. and i put 75 prim 80 sec. still got prblm...its back firing out of carb first with black smoke then caught on fire... so i think i said before i had 50cc pump but i might be wrong which ever one is the smaller im thinking 30cc?? so ima try the bigger acc. pump see where that takes things now