the carburetor most likely needs to be re-jetted,i would only recommend going 1 or 2 sizes up.i would also recommend getting a better exhaust while your at it if you haven't gotten one already.rocky mountain atv should have what you need,i have shopped with these guys numerous time with out disappointment.
p.s before doing any of this i would check your air/fuel mixuter screw,this can have the same effect as you explained.
best of luck
p.s before doing any of this i would check your air/fuel mixuter screw,this can have the same effect as you explained.
best of luck