Hi, im busy running in a RB C6; Im still in the very, very rich setting for, but i have found that my running temperature are already 130degC, It is very warm here temperatuers 32degC high Humidity.
Now its time to start leaning it out, but the temperature will surely go to high if i do this. Do i change the plug for a colder one, right now im running the #6 (medium); If i change to a #7(cold) plug will this cool the engine down enough?

what kinda of fuel do you run?

are you sure you dont have an airleak?

does it idle good?

Fuel is 25% nitro "Flash" only fuel availible here, everybody is running this. Idle is very smooth, i dont suspect a air leak.

the thing i've found with all the RB's that I've owned is that the temp during break in does tend to get a little high but then all of a sudden they drop like 40+ degrees thats when I know it's ready for the race tune it's happened with every RB I've owned. Just keep it where it's at and run some more fuel through it thats what I was told the first time I broke one in and was worried about the same thing you are right now. I did and it worked out great. hope this helps