i got a 90 yz250.. fresh rebuild and cleaned carb! and it is doggy out of the whole and then will rap up good but when riding on top end it will start to dog out a little bit again!!

what can cause this i just bought a new air filter im gunna try this.... wrong jetting???

its got a 400 main and pilot i am not sure on didnt look..
gas oil mixture??? please help thanks all

 

i would recomend testing your spark plug to sww if your too lean. just warm up, ride it all the way threw the gears, then when it starts to bog down pull in the clutch and hit the kill switch. then pull out the plug ad see what color it is. if it is white/tan too lean. if its black too rich. idealy your shooting for a marshmallow brown color. this will help oyu determin if you need to rejet