Booger, thanks for the pics and writeup, I've been toying with the same idea, TRX bottom end swap w/ kick start. I heard the same thing, that it didn't fit. If all that's different is the fr mm that's not a show stopper for me at all. Did you get the EX stator also, the charging system should be a breeze w/ that. I see no issues with making the charging/starting system just as reliable as the EX, it's going to take a decent battery though, KTMs been doing it with the RFS models for years with a small battery. The XR4 airbox w/ the top removed looks like you could fit a KTM sized battery and solenoid suspended in there just like they do on the RFS models, should be an easy bracket fab. The PO cut the top out of my XR4's airbox and it's not been an issue in deep water nor NMs dusty desert conditions with a twin air filter. PM me if you end up making your own harness and need any info/ideas, I've built a few for some XRs that worked out pretty well and got some diagrams that may help you out.