I have a YS 61 FR (YS0090) that I bought about 12 years ago. It doesn't have a lot of time on it, and I've always had to set the needle right on the edge of lean or it would flame out in the air. The needle is showing some wear where it seats. I have to close it almost all the way or the engine is too rich. I'm running a 12x10 APC with a CF pipe (don't remember the company), 15% Cool Power, getting 10K RPM. Power and throttle response are good.

I can't find parts on the web. Where can I order a replacement needle?

Call YS Parts at 775-782-4562 They have the parts in stock.

Thanks, Dave.

It's been a long time since I set up a pipe. Is the right approach to adjust the length to get the peak RPM? How much change should be expected between the "wrong" length and the "right" length? If the pipe is too short would I expect sensitivity problems? Is 10K with a 12x10 APC and 15% fuel at sea level with dry air (Silicon Valley) about what I should expect?

The rpm you are getting is about right. To test for correct length, pick up a bigger prop than you are now running, say a 12x11. Run each of them and see how the engine behaves. If you are too long for your current prop, the bigger prop will still needle and run OK. If it's fussy your current prop should be about right. Another way to tell if you are too long is if the engine richens up in level flight after taking off. If too short, the engine will lean out when you pull vertical.

Good Flying!