Bought a 91 xt350 from a guy who put aftermarket DG silencer. He never got around to jetting it. It wouldn't hardly run so I took the carb out, it had a 125 main jet it in which I changed to a 122 and he had washers under the needle since there are no adjustment slots. Took those out now it runs good till about half throttle and then sputters really bad. What should be my next step as I have almost no experience in this area.