Yes bored carb. First time I bored one and was worried that I ruined it from going so large but it runs well. 38 jet, 140 e-tube and I opened the pilot jet to .018".
I thought about boring one, but after some research, I bought a .670. I put it on the basically stock 224 at the time, jus a head gasket change to 9.3:1 cr, 26* timing, pvl flywheel, and header. I couldn't not believe how much more snappy the throttle was, instant acceleration, and that was with gov set at 4500. It made such a difference I went from a 5.55 gear to a 5 gear. Only a .035 jet for the basically stock engine. Its not stock any more and runs a .038 jet and 29* timing. My son has a .615, ducar 212, and my friend has a .640, pred 224. They all have different size air bleeds, but all have .022 low speed jets. I'm not sure about the e tube differences. The suppliers said they would not run with stock air boxes, but we do every day. My friends still running his stock 224 muffler. The idle is loppy and rich, but we have not fouled a plug, loaded cylinder with gas, or blow black smoke, and super ez to start. Imo, the bored stock style carbs are the best single improvement or upgrade you can do with these clone engines, stock or modified.