[atomikitten]

they say don't use the new big mini-bike large CIMs for the provided kit transmission for a number of reasons. The RPM and torque are different, they draw different amounts of current, the size of the output shaft is different...
Yes, you can compensate for all of these things, but why would you? There's a conversion kit made my AndyMark. Trying to use the mini-bike CIMs with the kit transmission is a bad idea; it's not designed to work that way. If you want to use the mini-bike CIMs, it's better to use their conversion kit because a professional has already done the work for you.