Perhaps someone can offer a tip or two. The motor is brand new and was bench run - about 1/2 a gallon pretty rich with cool down periods in between 11 oz tank fulls. its now on the airframe and has dead sticked on me once. I decided to tune it better for the next flight. I have managed to get a great transition from idle - which is really slow if I want to a max of 9100 rpm with a 16x6 APC on 5%nitro 20% castor fuel. The problem is the mid range - from about 4500 rpm - if its left around this setting or even up to 6000 rpm it starts running richer and richer until it eventually bogs when you open the throttle and sometimes cuts. This is waht happened on flight one with a far richer main needle setting. The plane was a brand new F90 and I didnt want to rip the wings off so I throttled back and after a few mins she styarted sounding really rich and she cut. Any ideas, anyone[]?