I have a CCRC 50 that has been running great. It has about 1 hr run time on it. It starts easily and has good power.
Idle is almost a tickover and can almost see the prop. The issue is that in the mid range for power back flying there is infrequent bark in the exhaust. Doesn't affect reliability and I am sure this is a fuel mixture as the engine is breaking in. But this begs the question? High speed or Low speed needle? I don't want to get too far off of where it is now as it has vertical power for a 16.5# bird and great reliable idle. Just annoying the bark in the exhaust that should not be there.

Oil/fuel. Full synthetic 2 stroke racing oil 2 oz conventional 2 stroke oil 1 1/4 oz to 1 gal of gas.

Any thoughts. Really hard to get to the needles with the cowl on so the adjustment must be made cowl off and then tested.


I considered the static pressure on the diaphram but this bark will occur in straight level power reduced flight. During maneuvers the power pulls strong with no bark. This is why I am guessing it is just a tad bit rich in mid range and wondering which needle to adjust. Thank in advance.