Hi Grumpy , I just rebuilt a honda gxv 120 which had no carby ,fuel tank or throttle mechanism or control plate so I had a sanli powercut donar with a huayi carby. I put only one o-ring with new idle jet. After new piston rings etc all put back together minus cowl and pull start etc it worked perfectly. This was a fun little job till I get original parts.
The new idle jet was a very tight fit so I didn't think it would work in the huayi carby but it did perfectly, the original huayi idle jet looked a little different to the new one ( the metal jet insert )which you can't really see that good . The one on the left is original huayi idle jet. [Linked Image]
[Linked Image]