I have noted on my recently acquired 415C, that the C-85 has a moderate amount of vibration between 2100-2300 RPM. We re-positioned the prop to the proper position on the hub, but no difference. The motor mounts are good and there doesn't seem to be a lot of filing that would put the prop out of balance. The next step would be dynamic balancing. But, is there any known inherent vibration in the C-85's in that rpm range? Any other thoughts?
Craig N87018
