gas bike elect. prob.

I've had a 66cc gas bike 2 cycle for some time, never had a problem outher than a dirty spark plug once in a while. Now i can't get spark, Replaced cdi spark box! Still same problem, Checked magneto - Puts out 24volts AC still have a problem! No spark! any ideas? I'm stuck thanks Bugman

hows your kill swith wiring , its not shorting you out somewere is it ?
bad plug ? stick a bolt in plug wire cap , instead of a sparkplug and see if you visually see a spark come from the bolt off the top of the head