I looked up the part numbers and they are different, the XR being a 30400-437-013 and the 200X being a 30410-965-013. If memory serves me correct as far as plugging in they will interchange. At one time I had a 1981 XR200 (and soon will have it again) and the crank locked up so we tossed a well used 185S engine in it and it ran very strong for what it was. I'm wondering if it was just the bigger carb that did it or if the timing curve was a little hotter on the XR's to better match the hotter cam, bigger bore and bigger carb?