i have a baja 125 4stroke dirtbike it has run beutiful until now, i was riding this morning when the motor started cutting out but only on the top end, it idles fine until you give it gas then when it reaches higher rpms it spits and sputters and sounds like crap, i thought it might be a foul plug bought a new one same thing still runs like crap , then i took off the carburator took it apart and cleaned jets and all holes put back together and still the same any ideas what else i could try or what else this could be