just a few things I check first............
airleak ? = leakdown test
bad plug wire or boot= unscrew boot, cut off 1/2" off wire, re-screw boot on, or new boot
bad ground = check black wire at coil has tight connection to bare frame, remove end and clean
all cionnections from startor to CDI tight and clean
cracked or chipped reeds
fuel flow to carb
float height correct or sticking floats
carb cable routed correctly
air filter clean and oiled correctly
airscrew set between 1 and 2 turns out