I have a brand new 61RF with pump which I am trying to run in ... problem is that I can not get the engine to run stably when it is rich ... the engine starts well at idle with about needle open about 1.5 turn, and when I open the throttle, it goes to full throttle but when I try to adjust the needle so as to make the engine run rich at full throttle, it either becomes so rich that it stops by flooding or it runs at around 10,000 RPM ... I can not get it to run stably below 10,000 RPM - it just goes too rich and stops.

I am using an APC 13x8 with 80:20 Methanol and castor oil fuel for running in as I do with all my engines.

Any suggestions?