Piaggio Typhoon 50cc 2004 wont run?

my ped is fluding sum where, i have a piaggio typhoon 50 2004 and i have striped the carb,cleaned it and taken the head off and dont no what else to do it doesent all ways start first time but when i got it running. it ticks over fine but as soon as i put sum throtle on it, it back firses and then cuts out is there any sugests on what i could do?