They should fit if they are both Keihin carbs, but I don't recomend it because they are calibrated differently. Try this jetting, #160 main jet and a #50 pilot jet. Turn the mixture screw out 2 1\2 turns to start, then fine tune after the engine is at normal operating temperature. This jetting works great in my 03 yz450f. Keep in mind that air temperature, humidity levels, and altidude will all affect the jetting. So adjust your jetting as required for your riding conditions.