ORIGINAL: ameyam
ORIGINAL: CGRetired
My reasoning there was that I had recently ran an engine in on my front lawn (the plane was tethered to the ground and I ran the engine up through at least two tanks of fuel.. maybe three). My technique was full throttle with blubbering rich HS needle setting, with occasional excursions to lean for about 10 to 20 seconds, followed by blubbering rich settings.
CGr.
CGR, thanks for getting that out of my head. I have 2 engines -a 55ax and a 75ax, from my trainee days that have recently given me a lot of problems. I was told that this was becuase, like you, my instructor didnt run these in properly on the ground but rather, he set them rich and flew with them directly (no nose up flights though). Now that you have mentioned that this is also as less desibrble but acceptable practice for 2c engines, it will put mind to rest that I did not do wrong in not objecting to his impatience with the engines.
For the record, we too run the engines very rich and full throttle with intermediate leaning for 10-20 seconds like you said and I will ensure we do this with all further 2c engines
Ameyam
I also run them slightly rich even after break-in. I was taught to use the "pinch test" to set the high speed fuel mixture, and to leave it at that slightly rich setting. Some claim that if you can't see smoke when flying it's not rich enough. That may be, I don't know because I always set it rich enough that I will see smoke when flying. I've not set it to lean, at least not that I can recall.
The most difficult time in a flight is when headed straight up. The fuel has to travel up into the engine and tends to be somewhat lean because of that. So, that's one main reason to run them somewhat rich.
CGr.