Have you tested the coil? Might as well know for sure if its the coil or not.
Check this Vid out by Jetlee
https://www.youtube.com/watch?v=OANfjyXJaDU
And heres where you can buy a new one
http://americansportbike.com/newdir/Item/17346
otherwise check with paulpud the couple of others that sell parts. Or Ebay