I have never ridden a kz. I’d love to try an icc engine but haven’t yet.
Anyways here is my opinion.
I do like the purpose built kz’s for a couple of reasons. exhaust coming out the rear. air intake in the front. no burns off pipe…. less clutter…. and ram air effect.
I also look at the cr125 like this. that motor was most likely in development in the late 80’s or early 90’s at best. Technology has changed enormously since then yet those motors are basically still running off that early design. Now think about this for a moment. Computers and computer aided design was like unheard of back then. Hell the world wide web didn’t even exist. Cell phones… nope. This kind of illustrates the massive changes since then. If you put a little thought to that you can envision that design and manufacturing improvements must have improved immensely along with it since then. A newly designed cr motor i’m sure would be much better. Now compare that to a kz motor that has been designed with the newest available technology and i’m sure there is a stark contrast.
With that said I just bought a swedetech cr125 setup off a gentlemen on here. lol. Part of me wishes I opted for a tm icc motor but the Honda was available at the right time when I needed it so that is what I will run for the next couple of years. I am a newbie anyways so it won’t matter much i’m sure.