Hi,

My Fuji 50SB in my GP Christen Eagle II has had about 2 gallons of premium unleaded at 40:1 through it. It's turning an APC 20x8 prop.

Sometimes, especially after several minutes of flying, the rpm will surge back and forth (high-low-high-low, etc) when the throttle is in the mid-range area (not full throttle and not at idle).

I have heard a few theories from the guys at my field: "It's the servo-activated kill switch...disconnect it and it will stop." I disconnected it, and it is still there. Another said that "It's a Fuji....they do that until they are broken in." Another suggested that the low speed needle wasn't set right.

I don't know what would be causing it. It's just a little disconcerting when I'm on base leg ready to turn final and the thing is surging like crazy until I finally cut it to idle.

Any suggestions?

Thanks,

Rich

You may have the high-speed or low-speed needles a bit lean. If richening one or the other, or both, doesn't cure the problem, you'll have to disassemble the carb and clean the screen. The screen is under the cover with the big screw in the middle.