Electric problems on my Zongshen gs250 please help

I am having problems getting a strong/reliable spark on the Zongshen gs250 I have changed the starting coil and I have a measured amount of power coming out of the spark plug boot but no spark from the plug. If any one has had something similar happen to them please let me know or if any one has any idea. Please help

Move along the chain - CDI, coil, plug cap...

I have done this and I am getting 10-15 volts at the spark plug boot where I am supposed to get 100+ volts would you think this is a coil problem?