Good reading about the GMS .47 I have had nothing but trouble with it. Overheating is (was) the major problem. I tried drilling the fuel inlet nipple, muffler nipple, adjusting the low needle ... etc, to no avail. UNTIL, I found the real cause of it. As it turned out, I had several GMS .47 carbs to try and they all resulted in the same thing, the dreaded overheating. What finally woke me up and clued me into the REAL problem was that the high speed needle valve did not make any significant changes. Starting with 2 turns all the way to 12 turns open, the engine would run the same and then overheat. So, I took a closer look at the needle itself and found a small line/grove part way on the tapered needle. How did that get there you ask? ... well, I found that when I got a new carb out of the box and looked at it, it did not have the very small grove or line. How did that get there then. Manufacturing difference.. no, it was ME! When I began the break in process of the engine, I tightened the needle valve very tight just to find the zero position, so that I could get the correct number of turns to start ... approx 2 turns open. Well that did it, when you OVER tighten the new needle valve in the brass spray bar, which seems to be tapered inside, it puts that grove on the needle and from then on extra air enters that little space within the spray bar... in other words, the needle valve is damaged. I tried this with several carbs, and purposely destroyed a $9 needle valve to prove my theory.. and yep that did it. The good carb worked great, fabulous idle, quick transition, 14,400 rpms , temperature at 225 degrees and ran like the dickens and never overheated. Then to really mess it up, I tightned the needle valve past the stop point to crank it in real tight and then took it out and noticed a grove/line on the needle valve. Ran the engine again and alas, it overheated in a few minutes and the needle valve did not make much of any difference. Also, a note/warning, when you screw in the high speed needle valve to the stopping position make SURE that the carb barrel is open, otherwise the low speed tube/bar touches the end of the needle and may cause damage to either component. I learned that the hard way, only after the needle is open a couple of turns, should you close the carb barrel. Voila, it runs like a top and cost me a few needle valves and spray bars... what a nightmare. Thanks