ORIGINAL: alan0899
G'day Mate,
I don't believe you are using a prop that is too big, but 10% to 15% nitro will probably run better, check out this Saito page,
http://saito-engines.info/prop_sizes.html
The problem is, that with 30% nitro, the OS F plug, is too hot for that fuel, too use 30%, you would need a colder plug.
Thanks! I try cooler plug and see how it works if not, then less nitro.