will any year 250r motor fit in my 85 frame without any custom motor mounts? second question is which internals are interchangeable for my 85 motor. can any year top go on any year bottom?

 

Just 85 & 86 will bolt in the 85 frame without modifying frame and mounts. The 85 & 86 motors are the same and 87 - 92 are Totaly different and motor parts do not interchange with the 85-86. 87 -92 have a power valve and 6 speed tranny and different reed setup. Hope that helps.