I have seen some carts with Honda RS125 engines in them. I get some guys Emailing me to help them find nice engines for sale. I have never seen a 250 in a cart before. The 125 engines make enough power and are smaller and lighter than the V-twin NSR250 engines. Cart racing is fun! My neighbor does it and has brought me along a few times, those are some sickly fast little machines that will leave you with a big smile (and some people with poop in their pants)