Well, that was a pretty good read!
I'm only a few years behind here, but, when you don't have much money and you like to fly RC, you buy what you can. I bought this CRRC Pro gf40i last year and put it in a Sbach. It seemed to run well on the bench for the minutes I watched before buying it from the fellow. Once I had it on the plane, I only got two test flights. There was no power on either flight and I couldn't get the needles right. I just let it sit until now. As I read this thread, I went out to the garage and did some of the very basic fixes such as the tubing on the metering side of the carb, gapping the plug to .022, NGK plug (came with engine), correcting an air leak between carb/intake (due to long mounting screws), and setting the needles at L: 1 1/3, H: 1 3/4. The engine is starting and running easily now and has way more pep than when on the Sbach (just replaced with DLE 55ra). I am going to check/set the timing to 28*BTDC as my sensor mount is broke and I already have a new one made from fiberglass sheet. It's 2x as thick as the original but allows the sensor to set directly over the magnet completely rather than only about 1/2-2/3 over with the factory mount. I bet that will have her running like a striped ape.
Once all of this is done, I'll be mounting it on a brand new in package Great Planes Yak 54
http://www.greatplanes.com/discontinued/gpma1411.html . I think she'll pull it around pretty well. From the sounds of things, you who have completed these mods successfully have had a lot of use from you engine. It also sounds like it's pulling 12-15 lb models around fairly nicely.
Hope you guys are continuing to enjoy your engines. Mine had a Bowman ring put in right before I bought it so I'm still trying to get it broke in again. I don't think the whole engine has 2 gallons through it and there's less than 1 gallon since the new ring.
Thanks for doing all of the research for me.
Happy flying!