I have an 86 TRX350A Fourtrax 4x4. Sometimes it starts and runs fine, other times it will not start. After checking all the obvious and while checking the spark timing, I discovered that it sparks at times other than when it is supposed to. Has any one ever had this problem before? I am unsure whether to replace the CDI box, the pulse genarator, the stator, the flywheel or all of the above.