Well, I'm asking for help. Today the plane finally ran great and flew great until the end of the pattern, about four and a half minutes I began losing power. I'd pitch it up and get a quick burst of power that died off. My guess was it was going lean rather than rich from the sound and smoke. I think I was right.
Next flight I richened it up a half turn and suddenly the plane is doing 10 second laps. Very interesting to watch. I thought maybe I was super rich, but...I finally landed with motor still running as it died. It still had about one out of three ounces, so I know it was just idling beyond lean.
Next I started it and it was dying until I began richening it turn after turn until it was screaming lean. I kept turning the needle out until it was coming out. Still screaming lean.
My next course...and only course I can think of is to take the lines off the needle and blow some fuel through it to clear a presumed obstruction. I won't be able to test it until Friday at the field, so... anything else it might be?
The Details.
fp .25.
10/22 powermaster. I added 1:40 parts acetone to lengthen my run. I've done this only about four times and had fair results. Today being the first time it ran almost perfect, and then completely unusable.
ST. needle. I understand this is the wrong choice but the engine came with it. I can't tell the venturi size as I don't have the micro tools to measure. But...another question. If the venturi is too large, I must increase fuel to match, and possibly lose some power. Correct? If the venturi is too small, I must decrease fuel, and possibly lose some power. Correct? Until today the plane has been too rich, or too lean, with about three flights that were just right.
Sulivan 3oz tank set up for uniflow. I can visually inspect the clear tank and see that there are no bubbles going through.
Well, that's my story. I almost bought a new fp .25 but it sold because I thought I had put my engine trouble behind me. Hopefully it's just a clog of something that got in my fuel line.
Any thoughts and free education appreciated. I have about 20 runs in this engine in this plane and like I said, about three good runs. It used to run slobbery rich most of the time until today.
David