I have a Moki 2.1 that I had the problem of going rich after take-off. Since I was using a cline system I contacted Bill Cline for advise. He told me to mount the regulator so the vent in the regulator is pointed toward the rear of the aircraft. That cured the problem. The airstream was pressurizing the regulator.
I also found the best plug for me is the OS type F four stroke plug.
I use FAI fuel with all castor lube.