Looking at some CT100U photos may help.
https://www.google.com/search?q=Col...rfzZAhWIq1MKHYoKBsQQ_AUIDSgE&biw=1680&bih=936
If link doesn't work, just do an image search.
Depending on where you live, you might be able to find a parts bike on Craigslist for cheap. A used DB goes for more than a new Coleman in my area, but lots of members have found them for next to nothing.
As I said, I'm not 100% sure the Coleman or Monster Moto parts will work, but they sure do look alike. All three use a 12mm axle; all three use a 145/70-6 tire; the rotors look identical; the sprockets look slightly different but that's just cutouts (holes), or lack thereof (Coleman and MM are both 75t; don't know about DB). If you do order parts from Coleman (or MM), be sure to get everything you need in one order so you don't have to pay more shipping on something you missed. I have to think if you were to get all of the Coleman parts (or all MM parts), you would be okay. I think they're probably generic Chinese minibike parts, basically.
If you have replaced the original engine with something larger, you may want to consider a sprocket adapter and split sprocket with lower tooth count, instead of a 75t solid sprocket; requires adapter, split sprocket, bolt kit to bolt sprocket to adapter, bolt kit to bolt adapter to wheel (adapter requires longer bolts due to thickness); around $45 total. Search: doodlebug sprocket adapter
I'm done. Good luck!