i have a 73 harley cart and was running great. all of a sudden the motor started skiping. in forward and reverse. changed the plug, fuel and filters. i played with the timing back and forth, it helps one way and hurts the other. no matter were it is it still wont stop skipping or cutting out. also cleand the carb and checked the muffler for blockage. nothing. like i said it just happend out of the blue. also compression is good