MAD MUDDER· Registered
99% sure it is with the carb. cover some of your intake up and rev it up if it runs worse you are not getting enough air, if it runs better you are getting too much air. you can adjust all that with the air/fuel mixture screw. when i adjusted mine i just put the 4wheeler on car ramps and layed under it and adjusted it while it was running. go to the stock setting for the jetting, turn the screw IN untill it runs a little choppy, then write down how much you truned it. go back to the stock setting, turn the screw OUT untill it runs choppy, then write how much you turned it. then all you have to do is figure up what the setting is between the two extremes and that is where you will want your bike to run at. hope this helps.