OS 61 FX Needle setting
04-05-2006, 06:46 PM
#1
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OS 61 FX Needle setting
Hello Bax,
I have a new 61 fx, abaut 5 tanks in.
1. Last sunday I checked how far the needle setting was and I was suprised to see that it was only 3/4 turns out. The engine has good idle and at full throtle peaks perfectly only at this setting. I would like to know if its normal to have this needle setting?
2. On my last flight, my fifth tank since new, the engine started to quit after 3 or 4 min of flight time, I suspect it is because its too lean?
Help please.
I have a new 61 fx, abaut 5 tanks in.
1. Last sunday I checked how far the needle setting was and I was suprised to see that it was only 3/4 turns out. The engine has good idle and at full throtle peaks perfectly only at this setting. I would like to know if its normal to have this needle setting?
2. On my last flight, my fifth tank since new, the engine started to quit after 3 or 4 min of flight time, I suspect it is because its too lean?
Help please.
04-06-2006, 10:57 AM
#2
My Feedback: (11)
RE: OS 61 FX Needle setting
If you set the engine's high-speed needle on the ground so that it's rich of peak RPM when the tank's about 1/4 full and the model's nose-up, then it should not go over-lean in the air. If the engine goes lean in the air, then you have some kind of difficulty in the fuel system. Likely, you're getting vibration-induced fuel foaming, or something's not allowing the tank to pressurize properly.
You'll need to check everything carefully.
If the engine's set correctly, the exact number of turns on the needle is not anything to worry about. If you find the setting changing, though, then you need to start examining everything to find out why. If you find that, over time, the needle is actually needing to be turned in (leaner) to keep a good setting, then it means that the needle seat in the carb or needle housing is being damaged for some reason---usually vibration-caused wiggling of the needle, which bashes the needle seat. You can tell if that's happening because the pointy part of the needle will have a polished ring around it.
You'll need to check everything carefully.
If the engine's set correctly, the exact number of turns on the needle is not anything to worry about. If you find the setting changing, though, then you need to start examining everything to find out why. If you find that, over time, the needle is actually needing to be turned in (leaner) to keep a good setting, then it means that the needle seat in the carb or needle housing is being damaged for some reason---usually vibration-caused wiggling of the needle, which bashes the needle seat. You can tell if that's happening because the pointy part of the needle will have a polished ring around it.
