Originally Posted by Northern Dog
I'm gonna throw in my 2¢ worth at this point ...
I've seen problems in the past on bikes and cars where the ignition/spark would break down once you reached a certain rpm range. Have you tried swapping out the coil and/or CDI yet? ... it also may be something as simple as a faulty plug wire/cap.
+1 it`s a possibility,if the CDI is going send it to me for a free rebuild,i`ve rebuilt 7 so far in 2 months,more coming,and like i say i do it for free for guys here and at TT.....