Before I went and reproduced the needle valve, I figured I'd run this GMS .47 again and try different fuel to see if it made any difference. First fuel was 80/20 methanol/castor fuel. Max rpm was 14,700 using a 10x6 APC prop and red Jett muffler. I could get a nice low idle of about 2,800rpm. Setting the idle needle for a good transition meant it would load up at idle and stumble a bit throttling up from a long idle (30sec or so). Setting it leaner so it wouldn't load at idle meant it was lean in the midrange and would cut out. Opening the main needle didn't help. I tried some hotter glow plugs and that helped some plus gave a little better top end power, but it would still load up at idle if set for good transition. Next I went to the opposite extreme and put some 20/20 fuel in the tank. Top end power went up to 15,180rpm and throttling improved, but still would load up some. On both fuels, it took over a half turn of the needle richer to get a drop in rpm. For most of my testing today I set the needle right at peak just to ensure the top end would be clean and fast. I think re-profiling the needle may still be necessary, but I don't think it would be the very tip that it should be changed but further back a little to richen the midrange so the needle can be set leaner for idle. Thoughts?