Typically, I run 5% nitro 20% castor in most of my engines. I run 25% castor in my lapped iron/steel engines, and my bushed crankshaft engines. Nitro is expensive, so I try to use as little as possible. I've noted a 500-800rpm loss when running FAI fuel (true 80/20) even with some acetone in it, so I went back to 5%. I have tried higher nitro in my Enya 4-stroke .60, but it didnt run any faster or better with more nitro so I went back to my normal mix. I have been mixing my own fuel for two years now because a gallon of glow fuel costs me at minimum $32. My car fuel with 20% nitro and 12% oil is about $37 a gallon. Mixing my own, fuel costs me between $8 and $12 a gallon. I think I burned 6-7 gallons of fuel this year (about half of that was breaking in engines.. )
I went out to run the G51 some more, trying to get a picture of the carb ''spitting'', but none of my pictures captured the spitting fuel like Earl was able to capture. I was using a 1600 ISO setting as well.
Hsukaria - before I ran out of light for my tach to work, I ran a 10x6 APC on the little G51 and got 14,460rpm on 5% nitro 20% oil at 50/50 blend of castor/synthetic. (using up some experimental fuel). I also tried an 11x9 and 11x6 but it seemed overpropped with both of these props. The needle had to be very rich on the top, but transition ended up being pretty rich. I also tried the Fox method for setting the needle, and I lost almost 1000rpm when I removed the glow driver. The plug I was using was the same plug I broke the engine in on, which was used and abused to start with. I think it is a medium or medium/hot plug; not my normal hot plug that I usually use. Tomorrow, pending the rainstorm, I will try again with a new plug and my normal 20% castor fuel and run a few props.