I have a 1999 yz 125 and will run for a minute or so then bog down an die so I took the carb off and cleaned it and there was a broke main jet so I replaced it and then it ran better but still is having trouble running when you are riding it. It idles fine and is not fouling plugs! The only thing I could think It is is ether the wrong main jet size or a problem with fuel flow or maby reeds or possibly fuel to air ratio screw! I really need help with this!!!