RE: NEW KMP 95" B-25
2 YS 63's would work fine for the H9 B-25 and even the earlier version of the KMP 85" one, but like ALan and Rip stated, not for the 95" KMP. It would be marginal on the TF B-25.
Even on the 85" KMP, it would be kinda iffy. Im putting two saito 91's in the 85" KMP version. A YS 63 is about the same power output as a saito 72 I believe. I orginally considered using the saito 72's and actually bought a 2nd one to do it then thought about more and opted to use larger .91 motors. Mostly because of the MCA Rip mentioned, but also because they can spin a lot larger prop then a saito 72 can.