A very interesting thread indeed. I also have two GMS 47's. Both have run without adjustment right out of the box, including my latest with a rear mount needle valve. I tend to run them on about 7.5% nitro. (I mix my own buying 5 and 10%). I find that these engines need considerably less nitro. The power is superb and the enhancement to the models performance is very rewarding. One engine is in a Falcon Ready on floats, the other is in the 40 sized Ultra Stick.

Good flying to all.