After 30 minutes of hard riding the quad went into a rev limiting mode. I replace the reverse limiting sensor and did an over ride button and it worked great. Now, I have a new problem. I ride hard for 30 minutes and a backfire occurs and the engine shuts of and will not restart. The nextday The quad will startand runs perfect until 30 minutes into the ride and the symptom reoccur. I am thinking an electronic problem, coil, stator, cdi. Anyone have an idea to put me on the right track to fix?