In June 2020 I purchased an Orion RXB250L (223cc) from Orion Powersports. Beyond a few small issues, I've had a great time putting 2k miles on my little air-cooled dual sport.
I spent most of 2020 and 2021 making modifications to the lovable little CRF230 clone. If anyone cares, a full run down can be found on my instagram:
Ursa_Adv
Fast forward to 2021 and the announcement from Orion that a new frame & engine design would be used on the '21 model RXBs. Needless to say, I was extremely jealous of extra cc's, counter balancer, and sixth gear. I had seen Jack of All Master of None's Loncin RE250 (LX166FMM-3) swap, but not gonna lie....I wanted something more.
I looked at doing the Loncin swap with an Athena big bore and maybe an oil cooler. In the end however I kept coming back to wanting to do something more.
After hours of pouring over Orion documentation and my own bike, I came to realization. The '20 RXB250 is a rebranded X-Moto XB-39. But Orion put an air-cooled 223cc motor in it. That isn't what the X-Moto XB-39 comes with stock. Queue the google translate and some internet sleuthing and I discovered the answer to my swap problem.
The X-Moto XB-39 can come from the factory with 3 different engines. One of which is the NC250 ZS177MM commonly found on things like the SSR250/300, GPX250, and CSC RX-3.
Double checking all my measurements, knowing this would not be a cheap mistake if I got it wrong, I had a few adult beverages to think it over. About an hour later, I threw caution to the wind and pulled the trigger on an engine.
https://www.alibaba.com/product-deta...7bc23e5fICGgsj
Less than two weeks and 1k later, 88lbs of Zongshen 250 showed up on my doorstep.
This thread is going to my experiences swapping the NC250 into the XB-39 frame and, hopefully, provide a sign post for other bored lunatics
who decide to go down this path.