Your Rev limiter is RPM controlled and the ECM shuts off the spark, I don't believe that it has anything do do with your bike cutting out at 1/2 throttle. To much or to little fuel at mid throttle may cause it to die out. Try dropping the needle to lean it out a bit or pull the choke out when it starts to die out. Hope some of this helps. Water in the bottom of the carb will kill the bike as well .