I have a Novarossi 353 .12 Tuned Plus 2. I have been trying to lean it out as much as I dare but it will run out after 4.75 minutes.

It has a 5 finned manifold with (2660 pipe?).

If I try to lean the low end out more I see a rise in temp and I don't think its accelerating as well.
If I lean out the top end, its top speed is noticeably faster but temps are too high.
(I'm trying for the 120-130C range), but not above 130C.

I'll try using longer fuel line, although I wonder if that will make tuning more difficult.
Also what about these finned exhaust coolers. Do they really make a difference or are they used more as a exhaust filter.

Fuel is 16% nitro, 10% oil (5% Syn Oil, 5% castor oil).

Anyone have similar issues with their Novarossi 353, or other brand engines and how did you get around it.

Cheers.