Glad you found the problem.Ignition switch wiring wasn't soldered too well at the bottom of the switches either on these machines.I've found this to happen also. The air/fuel mixture screw normally sets between 1 to 1 3/8 turns out from a lightly seated position. You'll just have to play with it. Make sure the air cleaner is ok and the carb is clean,I'd pull the jets and clean to make sure,PLUS there is a small vent that has to be open on the carb bowl.Compressed air or carb spray may be needed. Good luck,hope the grand kids like the atv. OPT